| Internet-Draft | eXtensible Stateless Eqpt Data Exchange | August 2023 |
| Spencer & Guy | Expires 3 February 2024 | [Page] |
- Workgroup:
- Internet Engineering Task Force
- Internet-Draft:
- draft-guy-xfsp-01
- Published:
- Intended Status:
- Informational
- Expires:
eXtensible Stateless Equipment Data Exchange
Abstract
This document presents a binary IP-based protocol to facilitate interoperable communications between avionics equipment. The protocol is UDP-based, stateless, and broadcast. Messages consist of a common header followed by a series of parameters and related attributes. The parameters are always informational, e.g., indicating airspeed is 150 kts, but parameter attributes can be set to indicate intent, e.g., this parameter contains a new user selected value such as an instruction that deploys the landing gear.¶
Status of This Memo
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.¶
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."¶
This Internet-Draft will expire on 3 February 2024.¶
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved.¶
This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
1. Introduction
Historically, avionics equipment has used private protocols for device interconnection but the trend is towards open communication leveraging standard hardware. There have been various stages in the evolution of device interconnection from point-to-point analog communication to digital serial protocols, to bus-based solutions and currently IP-based over ethernet.¶
One of the concerns with all of these protocols in this industry is that extensive testing is required, so developing a common protocol and library with its extensive test cases will improve time to market, product quality, and hence lower cost and improved safety.¶
The eXtensible Stateless Equipment Data Exchange, XSEDE, is such an IP-based protocol which provides a common means that facilitates parameter communication between airborne equipment. It is an open protocol which operates using binary-encoded UDP packets sent on a broadcast interface, typically using multicast Ethernet. This approach allows the avionics system to function as a collection of safety-critical microservices with XSEDE at the hub of the entire avionics system. XSEDE can flexibly drive multiple displays and unify all the aircraft's subsystems all at the control of the system integrator.¶
Parameters generally fall into two separate categories: schedule-driven and event-driven. Schedule-driven parameters are those that are sent periodically by the nodes in the system. One example could be the current heading might be reported by a sensors at 10hz. These parameters have a logical expiration time associated with how long they are valid, for example, 250ms. Another example could be the current air temperature or even the current value of the pilot’s desired heading (heading bug.) Event driven parameters are those that occur in response to an external stimuli, e.g., a pilot action on a switch, or an autopilot deciding to change the heading due to reaching an intermediate waypoint. These parameters do not have a logical expiration time associated with how long they are valid.¶
1.1. Basic Properties
XSEDE is a simple and compact protocol which uses a fast marshaling approach. Parameters may be coalesced, size and time permitting, into a single message to make transport more efficient. The message layout considers quad word alignment issues which can affect performance, especially on ARM-based architectures and pads to maintain efficiency. All messages are broadcast to all receivers so that the protocol is stateless and only the recipient controls whether a parameter will be processed. Since avionics software is subject to intensive testing and validation, XSEDE is designed to be deterministic with the fewest number of formal requirements required for implementation while still permitting the addition of new data formats and parameters through an extensible data model. Such additions can be made either through a future version of the standard or just through localized additionally configured data elements.¶
User and System selected events can exhibit two distinct behaviors: an event that cause an immediate change, e.g., a radio frequency change, and those changes in which a change may take time to be reflected by the system, e.g., selecting a new flap position. In the former case, only one parameter is defined: a request would set the confidence field to USERSEL (or SYSSEL). At the same time, the radio would periodically report with the current setting. In the latter case, these settings are implemented with a pair of parameters, a request (REQ suffix) and a current state Parameter that has no specific suffix. For example, FLAPREQ and FLAPPOS (See Section 3.5) where the first indicates the requested value and the second indicates the actual value.¶
1.2. Drawbacks
XSEDE is a UDP-based protocol so packet delivery is not guaranteed. However, since XSEDE is typically run on a purpose built network within a specific aircraft, the reliability of the network is still typically very high. Application-level behavior is implemented to ensure critical requests are executed. Since the protocol is stateless, it relies on the requestor to monitor status to ensure an action was taken. For example, if a request to put the landing gear down is made, the requesting application must watch reports of the landing gear position and alert if the request is not satisfied in a timely manner. However, you would be able to see if your request was correctly interpreted by a report, periodic or in response to the event, by the responsible nodes. Notably, the protocol does not contain the concept of incrementing or decrementing a value, just setting a specific value. A user interface which is designed to increment and decrement a value based on a user turning a knob, for example, must track the current value and when an increment is detected, transmit the new, incremented value with the appropriate confidence (most likely USERSEL). If two or more applications are monitoring the same knob from two different computers, they each would be able to redundantly send the same new value without affecting the behavior whether one, two or more such applications were concurrently running.¶
1.3. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
- Message:
- is the basic unit of communication in XSEDE.¶
- Node:
- is a device or process that implements XSEDE.¶
- Parameter:
- is the task specific payload contained in a message.¶
- Attribute Format:
- are the simple and structured data types associated with a parameter attribute.¶
- Attributes:
- are the values associated with a parameter.¶
- Dictionary:
- is a set of allowed values associated with an attribute, parameter, or message field.¶
- Source ID:
- Refers to the unique number which identifies the node, by convention with the top octet representing the computer and the bottom octet representing the application number within that computer.¶
2. Overview of XSEDE Protocol
The eXtensible Stateless Equipment Data Exchange is designed to operate on an airborne platform network. This network is intended to be isolated from the general Internet and comprises instruments, displays, sensors, and actuators performing various functions. XSEDE messages are broadcast to every node on the network. XSEDE message occur in three classes: Maintenance, Operational and Raw.¶
Maintenance and Operational messages consist of a header followed by a series of parameters. Parameters always represent information, a message is purely a collection of parameters. However, the confidence field must be interpreted to determine intent, i.e., the SYSSEL and USERSEL confidence levels MUST be interpreted by responsible nodes to affect changes on the relevant items.¶
XSEDE is stateless. There is no required protocol level response to any command, however, informational responses may be made. For instance, a command to change the radio frequency of a certain radio may generate a application-level response indicating the new radio frequency. All XSEDE messages go to all nodes which simply discard things they don't care about.¶
Raw XSEDE messages consist of a message header which specifies the length of the raw data, followed by that raw data. Raw data is classified as MIL-STD-1553, CANbus, digital samples, or other serial or streaming unframed data.¶
Each node in XSEDE is assigned a source ID. These Source IDs MUST be unique within the XSEDE network. The Source ID and the message number uniquely identify the message and are contained in the message header. Message IDs created by a node MUST be monotonically increasing. A receiving node MUST ignore all duplicate messages. The Source ID and a message number are used to ensure messages are processed in order and only once. Messages MUST be processed in order skipping any missing messages and MUST only be processed once. Senders and Receivers must account for integer overflow in message numbers. There is no retry mechanism at the protocol level; Missing and out-of-order messages SHALL be considered lost and if received out of order, a message MUST be ignored.¶
In addition to the Source ID and Message Number, The XSEDE message header also contains the message class, the Message Operation ID, DO-178 certification level, [DO-178C] the confidence level and the payload length.¶
For best performance, an XSEDE goal is to not send IP datagrams that have to be fragmented. Packets which exceed the MSS size will be fragmented. To achieve this goal XSEDE messages SHOULD be less than the network Maximum Segment Size (MSS) size in length. On a modern Ethernet network, IEEE 802.3 [IEEE8023] specifies a maximum payload size of 1500 bytes. The size of the fixed IPv4 header is 20 bytes [RFC0791] or in IPv6 the fixed header is 40 bytes [RFC2640] UDP headers consume 8 bytes, [RFC0768] the XSEDE header Section 3.1 uses 12 bytes leaving 1460 bytes for parameters or 1440 bytes on an IPv6 network.¶
3. Message Format
3.1. Message Header
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| src id | message number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg class | message ID | flags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| tcid | len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
...
: Data :
...
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
XSEDE messages are formatted as shown in the above diagram and consist of the following fields:¶
- src id:
- UINT16; locally configured source ID. Must be unique on network.¶
- message number:
- UINT16; monotonically increasing message number.¶
- msg class:
- UINT8; The message class. See Table 1¶
- message ID:
- UINT8; msg-op; See Table 2.¶
- flags:
- UINT16; See Table 3.¶
- tcid:
- t-NONE; See Table 4.¶
- len:
- UINT16 ; length of all parameters or raw data in bytes. Note: Operational and Maintenance class messages shall always have a length that is a factor or 4.¶
- data:
- 1*(parameter) / *(OCTET) ; raw data may be arbitrary length sequence of octets.¶
3.1.1. Message Header Dictionaries
This section defines the dictionaries used in the message header. See Section 3.1.¶
Table 1, below, shows the values defined in the msg-class Dictionary. These values identify the message class: raw, maintenance or operational.¶
| Name | Value | Definition |
|---|---|---|
| MAINT | %d2 | Maintenance Message |
| OP | %d3 | Operational Message |
| RAW | %d4 | Access to raw data stream (e.g., RS-232, RS-485, ARINC-429, etc) |
Table 2, below, shows the values defined in the msg-op Dictionary. These options further refine the operational message class.¶
| Name | Value | Definition |
|---|---|---|
| FLIGHTDATA | %d2 | Flight Data Info |
| DEVSTATUS | %d3 | Device Status |
| GDL90 | %d4 | GDL-90 Format Messages without framing, FCS or escape characters. [GLD90] |
Table 3, below, shows the values defined in the msg-flag-cert Dictionary. These choices represent the message and parameter certification level tracking with respect to the [DO-178C] specification. The message value represents the certification value of the transmitter, where the parameter value represents the source data node's certification value.¶
| Name | Value | Definition |
|---|---|---|
| EXPERIMENTAL | %d0 | Experimental |
| LEVEL-E | %d1 | DO-178 Level E |
| LEVEL-D | %d2 | DO-178 Level D |
| LEVEL-C | %d3 | DO-178 Level C |
| LEVEL-B | %d4 | DO-178 Level B |
| LEVEL-A | %d5 | DO-178 Level A |
Table 4, below, shows the values defined in the tcid Dictionary. XSEDE transcoder ID values or NONE if no transcoder.¶
| Name | Value | Definition |
|---|---|---|
| NONE | %d0 | No transcoder ID is required or asserted |
3.2. Message Parameter Format
The section defines the elements common to all XSEDE parameters.¶
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
...
: Parameter Data :
...
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- Unit:
- UINT16 If appropriate, which unit this parameter applies (e.g., Engine #1).¶
- SubUnit:
- UINT16; If appropriate, which subunit this parameter applies (e.g., Engine #2, Cylinder #3).¶
- Parameter Ident:
-
UINT32; This attribute is the composite of the length and a parameter specific identifier.¶
Nodes MUST compare to their known parameters to this value as a whole; that it to say, an Ident with a different length is a different parameter. This same Ident with a different length situation commonly occurs when sending range parameters but it also can happen when parameter definitions are updated.¶
If the combined value does not match a known parameter/length pair, the parameter data length MUST be determined, then padded to a multiple of four, and the parameter MUST be ignored.¶
- Len:
- 11 bits; Parameter Data Length in octets. This value MUST reflect the usable length of the parameter data, not including padding, however, the parameter itself MUST be padded to a length that is a multiple of four bytes to maintain proper word alignment.¶
- Ident:
- 21 bits; XSEDE Parameter Identifier. See Section 3.5.¶
- Format:
- param_format (OCTET): Format of Parameter Data. See Section 3.3.¶
- Confidence:
- param_confidence (OCTET): Confidence of data element. See Table 5.¶
- Expire:
- OCTET; Time to live. %xFF to not expire. See Section 3.2.2 for encoding.¶
- Pflags:
- msg_flag_cert(OCTET) Reserved Flags, bottom three bits are certification level of data. See Table 3¶
- Parameter Data:
- *(OCTET) quadword padded payload.¶
3.2.1. Parameter Header Dictionaries
Table 5, below, shows the values defined in the param-confidence Dictionary. These options represent parameter format confidence levels.¶
| Name | Value | Definition |
|---|---|---|
| USERSEL | %d192 | User selected value at runtime. Note: expire value SHOULD be zero and MUST be ignored by receivers. |
| SYSSEL | %d224 | System selected value at runtime. Note: expire value SHOULD be zero and MUST be ignored by receivers. |
| HIGH | %d100 | Confirmed known value |
| UNANIMOUS | %d50 | Redundant data available and is rationalized |
| RATIONAL | %d40 | Data being rationalized from other data sources with normal sources ignored |
| VOTED | %d30 | Data is redundantly verified from identical instruments |
| SMOOTHED | %d20 | Smoothed/filtered version of raw data |
| RAW / REPORTED | %d10 | Raw or reported unchecked data |
| ESTIMATE | %d5 | Rough estimation |
| USELESS | %d0 | Value is missing or expected invalid and supplied for debugging ONLY |
The msg_flag_cert Dictionary is also used. See Table 3 for its definition.¶
3.2.2. Expire Encoding
Information provided in messages have a limited usability lifetime or time-to-live. The Expire field is used to indicate how long the associated parameter is valid. It is an eight-bit field that is split into an exponent and mantissa to provide the maximum range and precision within this small space. The upper four bits represent the the mantissa and the lower four bits represent the exponent. If the value of the Expire field is %x00, the value MUST be interpreted to mean "the parameter does not expire," otherwise the expiry time value MUST be determined by the following formula:¶
Expiration (milliseconds) = (16 + M) * 2^E which can be implemented with ( 0x10 | M ) << E¶
This approach give us the range of 17 to 1015880 milliseconds (about 17 minutes) with 0x00 reserved as "No Expiration."¶
0
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
| M | E |
+-+-+-+-+-+-+-+-+
For example, an expiry value of %x13 gives a mantissa of 0001 and an exponent of 0011 yielding a value of (16 + 1) * 2^E ms or 128 milliseconds.¶
Another example, a value of %xF7 which decomposes to a mantissa of 1111 and an exponent of 0111 yielding a value of (16 + 15) * 2^7 ms, or 3968 milliseconds.¶
The minimum value of %x01 which decomposes to a mantissa of 0001 and an exponent of 0000 yielding a value of (16 + 1) * 2^0 ms, or 17 milliseconds.¶
The maximum value of %xFF which decomposes to a mantissa of 1111 and an exponent of 1111 yielding a value of (16 + 15) * 2^15 ms, or 1015808 milliseconds, which is about 17 minutes.¶
A final example, %x00 which is a special case for "No Expiration."¶
3.3. Parameter Attribute Formats
The various attributes associated with parameters occur as both simple types, such as Integers and compound structures, such as Waypoints. This section defines the attribute formats that are used in XSEDE.¶
3.3.1. BOOL Parameter Format
Boolean Format¶
Parameter Identifier: %d1¶
Length: 4¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| bool-value | boolean | Zero for false, 1 for true, all others undefined |
Table 7, below, shows the values defined in the boolean Dictionary. These options represent the nominal boolean values.¶
| Name | Value | Definition |
|---|---|---|
| FALSE | %d0 | False |
| TRUE | %d1 | True |
3.3.2. UINT Parameter Format
Unsigned 32-bit Integer Format¶
Parameter Identifier: %d2¶
Length: 4¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| uint-value | uint32 | 32-bit Unsigned Value |
3.3.3. WAYPOINT Parameter Format
Waypoint on a Flight Plan¶
Parameter Identifier: %d3¶
Length: 80¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| label | 12*12(OCTET) | Name of waypoint |
| lat | int32 | Latitude of waypoint * 10,000,000 |
| lon | int32 | Longitude of waypoint * 10,000,000 |
| lonlen | int32 | Length of degree of longitude for this latitude in meters |
| alt | int32 | Altitude associated with waypoint in 0.1ft |
| minalt | int32 | Logical Minimum for Fix Crossing in 0.1ft |
| maxalt | int32 | Logical Maximum Altitude for Fix Crossing in 0.1ft |
| speed | int32 | Target indicated airspeed |
| magadj | uint32 | Original (VOR) or Current (GPS) Magnetic Deviation in 0.01 degrees of NAVAID |
| inbound | uint16 | Inbound course in 0.01 degrees |
| outbound | uint16 | Outbound course in 0.01 degrees |
| freqkhz | uint32 | Frequency in khz if this is a NAV AID |
| wtype | fms-waypoint | Type of waypoint |
| ctype | fms-container | Type of container |
| flags | fms-flag | Flags for the waypoint / leg |
| cumete | uint32 | Cumulative ETE from active waypoint in 0.01 seconds |
| cumdis | uint32 | Cumulative distance from active waypoint in 0.001 nm |
| container | 16*16(OCTET) | What container is this waypoint a part of (e.g., V431, ILS-18L, etc) |
Table 10, below, shows the values defined in the fms-waypoint Dictionary. These options represent the flight management system waypoint types.¶
| Name | Value | Definition |
|---|---|---|
| UNKNOWN | %d0 | Unknown or unspecified |
| GS | %x80 | Glideslope component |
| DME | %x40 | DME Component |
| TACAN | %x20 | TACAN Component |
| VOR | %d1 | VOR Component |
| LOC | %d2 | Localizer component |
| NDB | %d3 | NDB component |
| LDA | %d4 | LDA Component |
| SDF | %d5 | SDF Component |
| FIX | %d6 | Generic RNAV Fix |
| ILS | %d7 | Complete ILS system |
| AIRPORT | %d8 | An Airport |
| DIRECTFROM | %d9 | Starting point of a direct to |
| WEATHER | %d10 | Weather reporting station only |
Table 11, below, shows the values defined in the fms-container Dictionary. These options represent the flight management system container types.¶
| Name | Value | Definition |
|---|---|---|
| UNKNOWN | %d0 | Unspecified or unknown container |
| NONE | %d1 | No container |
| VICTOR | %d2 | VOR Airway |
| JET | %d3 | Jet Airway |
| AMBER | %d4 | Amber Airway |
| BLUE | %d5 | Blue Airway |
| GREEN | %d6 | Green Airway |
| RED | %d7 | Red Airway |
| Q | %d8 | RNAV Q Routes |
| T | %d9 | RNAV T Routes |
| STAR | %d10 | Standard Arrival Procedure |
| DP | %d11 | Standard Departure Procedure |
| APP | %d12 | Instrument Approach |
Table 12, below, shows the values defined in the fms-flag Dictionary. These options represent the flight management system waypoint and leg flags.¶
| Name | Value | Definition |
|---|---|---|
| NONE | %d0 | No flags or leg type known |
| LEGTYPE-VA | %d1 | Heading to Altitude |
| LEGTYPE-VD | %d2 | Heading to DME Distance |
| LEGTYPE-VI | %d3 | Heading to Next Leg Intercept |
| LEGTYPE-VM | %d4 | Heading to Manual Termination |
| LEGTYPE-VR | %d5 | Heading to Radial Termination |
| LEGTYPE-CA | %d6 | Course to an Altitude |
| LEGTYPE-CD | %d7 | Course to a DME Distance |
| LEGTYPE-CI | %d8 | Course to Next Leg Intercept |
| LEGTYPE-CR | %d9 | Course to Radial Termination |
| LEGTYPE-CF | %d10 | Course to a Fix |
| LEGTYPE-TF | %d11 | Tracking Between Two Fixes |
| LEGTYPE-DF | %d12 | Direct to a Fix |
| LEGTYPE-FA | %d13 | Course from a Fix to an Altitude |
| LEGTYPE-FC | %d14 | Course from a Fix to an Along Track Distance |
| LEGTYPE-FD | %d15 | Course from a Fix to a DME Distance |
| LEGTYPE-FM | %d16 | Course from a Fix to a Manual Termination |
| LEGTYPE-AF | %d17 | Constant DMA Arc to a Fix |
| LEGTYPE-HF | %d18 | Hold to a Fix |
| LEGTYPE-HA | %d19 | Hold to an Altitude |
| LEGTYPE-HM | %d20 | Hold to a Manual Termination |
| LEGTYPE-IF | %d21 | Initial Fix |
| LEGTYPE-PI | %d22 | Procedure Turn to Intercept |
| LEGTYPE-RF | %d23 | Radius to a Fix |
| FLYOVER | %x01.00 | If not present, fly by |
| DISC | %x02.00 | If present, Discontinuity before current waypoint |
| ACTIVE | %x04.00 | If present, this is the active waypoint |
| OBS | %x08.00 | If present, waypoint allows OBS to be set |
| FAF | %x10.00 | If present, waypoint is final approach fix or after |
| SUSPEND | %x20.00 | FMS sequencing is suspended at this waypoint |
| LAST | %x40.00 | This waypoint is the last one in the flight plan |
3.3.4. STRING Parameter Format
String of characters (may not have NULL termination)¶
Parameter Identifier: %d4¶
Length: length(data) + 0¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| string-value | *(OCTET) | Optionally NUL terminated [ISO88591] String |
3.3.5. CASMSG Parameter Format
CAS Message¶
Parameter Identifier: %d5¶
Length: length(data) + 4¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| level | cas-msglvl | CAS level |
| rsvd | uint8 | Reserved, set to 0 |
| flags | cas-msgflag | CAS related flags |
| label | *(OCTET) | Label for CAS Message |
Table 15, below, shows the values defined in the cas-msglvl Dictionary. These options represent the Message levels for CAS messages and checklist items.¶
| Name | Value | Definition |
|---|---|---|
| CLEAR | %d0 | Clear a previously issued CAS message -- issue from system only |
| DEBUG | %d1 | In-system debugging output only |
| LOG | %d2 | Log to system log, but do not display |
| MAINT | %d3 | Display only for maintenance purposes |
| STATUS | %d4 | Aircraft system status only |
| ADVISORY | %d5 | Advisory, flight crew should be aware, may require later crew response |
| CAUTION | %d6 | Caution, requires immediate flight crew awareness and later response |
| WARNING | %d7 | Warning, requires immediate awareness and response. |
| COMMENT | %d10 | Checklist Comment Associated with Previous Item |
| UNCHKITEM | %d11 | Unchecked Checklist Item |
| CHKITEM | %d12 | Checked Checklist Item |
| CHKBRANCH | %d13 | Checklist Branch Choice |
Table 16, below, shows the values defined in the cas-msgflag Dictionary. These options represent the Additional flags associated with CAS messages.¶
| Name | Value | Definition |
|---|---|---|
| AUTO | %x01 | Item is automatically checked/unchecked |
3.3.6. SINT Parameter Format
Signed 32-bit Integer Format¶
Parameter Identifier: %d9¶
Length: 4¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| sint-value | int32 | Signed 32-bit two's complement value |
3.3.7. BUS Parameter Format
Bus and Electronic Circuit Breaker Format¶
Parameter Identifier: %d10¶
Length: length(data) + 24¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| state | ecb-state | State of Bus (in terms of ECB) |
| ecbflags | ecb-flag | Flags regarding ECB state |
| involts | int16 | Input Volts on Bus |
| drawamps | int16 | Current draw on bus |
| maxamps | int16 | Max Amps on bus |
| champs | int16 | Caution high amps |
| clamps | int16 | Caution low amps |
| minamps | int16 | Minimum amps on bus (could be -) |
| outvolts | int16 | Output Volts on Bus |
| maxvolts | int16 | Max volts |
| chvolts | int16 | Caution high voltage |
| clvolts | int16 | Caution low voltage |
| minvolts | int16 | Minimum low voltage |
| label | *(OCTET) | Label for BUS Message (System/Item) |
Table 19, below, shows the values defined in the ecb-state Dictionary. These options represent the Electronic circuit breaker status.¶
| Name | Value | Definition |
|---|---|---|
| UNKNOWN | %d0 | Circuit is in an unknown condition |
| OFF | %d1 | Circuit is turned off |
| ON | %d2 | Circuit is turned on |
| UNDERCUR | %d3 | Circuit is on, <100ma current drawn |
| RESET | %d4 | Request Reset |
| FORWARD | %d5 | ECB is active logical FWD direction |
| REVERSE | %d6 | ECB is active logical REV direction |
| TARGET | %d7 | ECB is set by target, not ON/OFF |
| BRAKELOW | %d8 | ECB is set by target, not ON/OFF |
| SHORTED | %d128 | Short Circuit |
| OVERCUR | %d129 | Overcurrent (but not short circuit) |
| OVERVOL | %d130 | Overvoltage situation |
| DISABLED | %d131 | Disabled by state-fault |
| RUNAWAY | %d132 | Disabled due to runaway (trim/flaps) |
| COLLARED | %d133 | Should not reset in flight |
| JAMMED | %d134 | Mechanical Jam detected |
| PULLED | %d135 | Pulled |
| BACKFLOW | %d136 | Disabled due to reverse current flow |
Table 20, below, shows the values defined in the ecb-flag Dictionary. These options represent the Electronic circuit breaker parameter flags.¶
| Name | Value | Definition |
|---|---|---|
| INPUTVOLTS | %x01 | Input Volts field is valid |
3.3.8. RANGE Parameter Format
Range description format¶
Parameter Identifier: %d11¶
Length: 24¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| numticks | uint16 | How many valid ticks are in the parameter data |
| units | param-units | Specifier for units for display |
| divisor | int32 | For display purposes, what are logical divisions |
| minval | int32 | Minimum valid value |
| maxval | int32 | Maximum valid value |
| mindisp | int32 | Where display starts (values lower than this are clipped) |
| maxdisp | int32 | Where display stops (values higher tha this are clipped) |
| ticks | starray | Actual tick data representing the scale marks |
Table 22, below, shows the values defined in the param-units Dictionary. These options represent the Units for the encoding and translation of XSEDE parameters.¶
| Name | Value | Definition |
|---|---|---|
| UNSPEC | %x00 | Units not specified |
| INHG | %x00.01 | Use inches of Hg for BARO/MANPRES |
| FT | %x00.02 | Use feet for altitude |
| NM | %x00.03 | Use nautical miles for distance |
| C | %x00.04 | Use celsius for temperature |
| LBFT | %x00.05 | Use pound-feet for torque |
| S | %x00.06 | Use seconds for time |
| A | %x00.07 | Use amps for current |
| V | %x00.08 | Use volts for voltage |
| LB | %x00.09 | Use pounds for weight |
| IN | %x00.0a | Use inches for distance |
| FPM | %x00.0b | Use feet per minute for rate of climb/descent |
| LBPH | %x00.0c | Pounds per Hour for fuel flow |
| DEGPS | %x00.0d | Degrees per second for attitude change |
| DEG | %x00.0e | Degrees for attitude |
| G | %x00.0f | G force for load |
| RGBA | %x00.10 | 8888 RGBA Value |
| KHZ | %x00.11 | Kilohertz for Frequency |
| PCENT | %x00.12 | Percent of Maximum |
| KT | %x00.13 | Knots for Speed |
| NMPLB | %x00.14 | Nautical Miles per Pound |
| KTPS | %x00.15 | Knots per second |
| MACH | %x00.16 | Speed of sound |
| CPM | %x00.17 | Count per minute |
| PPM | %x00.18 | Parts per million |
| LPM | %x00.19 | Liters Per Minute |
| KW | %x00.1a | Kilowatt |
| AH | %x00.1b | Amp Hour |
| HPA | %x80.01 | Use Hecto pascals for BARO |
| M | %x80.02 | Use meters for altitude |
| SM | %x80.03 | Use statute miles for distance |
| F | %x80.04 | Use fahrenheit for temperature |
| NWM | %x80.05 | Use Newton Meters for torque |
| PSI | %x80.06 | Use PSI for MANPRES |
| MPH | %x80.07 | Use miles per hour for speed |
| SMPLB | %x80.08 | Statues Miles per Pound |
| MIN | %x80.09 | Minutes |
| HR | %x80.0a | Hours |
| HP | %x80.0b | Use Horsepower for power |
| KG | %x80.0c | Use kilograms for weight |
| UL | %xff.ff | Unitless |
3.3.9. GPIO Parameter Format
GPIO summary format¶
Parameter Identifier: %d12¶
Length: 12¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| features | uint32 | 4-bit Feature (XFS_GPIO_FEATURE_*) x 8 |
| outmodes | uint32 | 4-bit Output modes (XFS_GPIO_OUTPUT_*) x 8 |
| inmodes | uint16 | 2-bit Input modes (XFS_GPIO_INPUT_*) x 8 |
| flags | uint16 | Reserved for future use |
3.3.10. APP Parameter Format
APP status format¶
Parameter Identifier: %d13¶
Length: length(data) + 56¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| state | scb-state | State of application* |
| rsvd | uint8 | Reserved bits |
| appflags | uint16 | Flags regarding app |
| period | uint16 | Baseline runtime period (XFS_SCHED_PERIOD_*) |
| avgcpu | uint16 | Average OS CPU time utilization in units per period over last second |
| hwcpu | uint16 | High water OS CPU time utilization in units per period |
| cpulim | uint16 | Limitation of OS CPU time utilization in units per period |
| runtime | uint16 | Max allocated runtime (per period) |
| deadline | uint16 | Deadline for completion (per period) |
| avgruntime | uint16 | Average runtime over last 1s |
| hwruntime | uint16 | High water runtime |
| ivcsw | uint32 | Involuntary context switches |
| aircraftid | 16*16(OCTET) | Aircraft Identifier |
| swrev | 16*16(OCTET) | Software Version Identifier |
| label | *(OCTET) | Name of APP |
Table 25, below, shows the values defined in the scb-state Dictionary. These options represent the Software circuit breaker states.¶
| Name | Value | Definition |
|---|---|---|
| UNKNOWN | %d0 | State of software is unknown |
| STARTING | %d1 | Application is in startup phase |
| RUNNING | %d2 | Application is running |
| STOPPING | %d3 | Stopping has been requested |
| RESTART | %d4 | Restart Application (PULL + RESET + START) |
| RESET | %d5 | Allow application to be started |
| HUNG | %d6 | Application is running but is no longer responsive |
| DEGRADED | %d127 | Application is running in a degraded mode |
| STOPPED | %d128 | Application is stopped |
| STARTFAIL | %d129 | Application failed startup |
| RUNAWAY | %d130 | Application has a runaway loop |
| OVERCPU | %d131 | Application is using excessive CPU while in RUNNING state |
| OVERMEM | %d132 | Application terminated due to memory overrun |
| EXCEPTION | %d133 | Application terminated due to runtime exception |
| ENDED | %d134 | Application ended without error or request |
| ENDERROR | %d135 | Application ended with error condition |
| PULLED | %d136 | Application should not be allowed to run until reset |
| COLLARED | %d137 | Should not reset in flight |
3.3.11. WBRANGE Parameter Format
Weight and Balance Range¶
Parameter Identifier: %d14¶
Length: 16¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| flags | uint16 | Flags if any |
| numslices | uint16 | Number of slices specified |
| maxtakeoff | uint32 | Max takeoff weight |
| maxlanding | uint32 | Max landing weight |
| maxzerofuel | uint32 | Max zero fuel weight |
| slices | starray | Slices that form weight and balance envelope |
3.3.12. UPDATE Parameter Format
Aircraft Update Progress¶
Parameter Identifier: %d15¶
Length: length(data) + 56¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| aircraftid | 16*16(OCTET) | Aircraft Identifier |
| progress | uint32 | Progress |
| progflags | msg-cmd-updstat-flag | Progress Flags |
| activity | 32*32(OCTET) | Description of current activity |
| label | *(OCTET) | Name of CPU being updated |
Table 28, below, shows the values defined in the msg-cmd-updstat-flag Dictionary. These options represent the Maintenance mode status update flags.¶
| Name | Value | Definition |
|---|---|---|
| SUCCESS | %x01 | Update is complete and successful |
| ERROR | %x02 | Error during update |
3.3.13. SERVO Parameter Format
Position with flags to interpret whether servo should be engaged, disengaged or left alone and whether active¶
Parameter Identifier: %d16¶
Length: 8¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| servopos | int32 | undefined |
| servomode | afcs-servo | undefined |
Table 30, below, shows the values defined in the afcs-servo Dictionary. These options represent the Servo engagement flags.¶
| Name | Value | Definition |
|---|---|---|
| ENGAGE | %x80.00.00.00 | If present in engagement request, along with 'ENGAGED' value, set engagement status |
| ENGAGED | %d1 | For requests, retain current engagement state, for status, present if currently engaged |
| DISENGAGED | %d0 | If engaged, disengage and for status, currently disengaged |
3.3.14. DBASE Parameter Format
Database Information¶
Parameter Identifier: %d17¶
Length: 92¶
Structure:¶
| Item | Type | Description |
|---|---|---|
| crc | uint32 | undefined |
| name | 16*16(OCTET) | Name of database (e.g., com) |
| supplier | 16*16(OCTET) | Who supplied the database |
| region | 16*16(OCTET) | What region is the data valid |
| cycle | 16*16(OCTET) | What cycle |
| valid | 12*12(OCTET) | date at which validity begins YYYY-MM-DD string |
| expires | 12*12(OCTET) | date after which data has data YYYY-MM-DD string |
3.4. Parameter Ranges
All parameter attributes values are typed, but some are further constrained to certain ranges. The ranges may limited in both value and for display purposes. The display 'ticks' can define various classifications such as a green, yellow, or red range. Furthermore, ranges can change over time. For instance, good oil pressure for a cold engine may be normally higher than that for a warm engine and a special parameter can be broadcast to indicate a range change. Table 21 defines the RANGE parameter format.¶
Parameters that have a default range have that range described in the next section. The default range will be displayed in tabular format. Many parameters have default and unchangable ranges, while others have daynamic ranges. Parameters that have dynamic ranges use a parameter that only differs in the length portion of the Parameter Data Len & Ident attribute. and having a RANGE attibute as its payload. The receiving node MUST distinguish between the value and the range parameters by examining the length portion of the parameter's attribute. Should a parameter attribute value be outside the permitted range. the value MUST be ignored.¶
In the style of the next section, a generic range parameter is defined below:¶
3.4.1. Sample Range Parameter
3.4.2. Ranges
This section defines the default attribute ranges that are used in XSEDE.¶
3.5. Parameter Types
This section declares the initial set of XSEDE parameters. Each parameter is defined by a name and a short description. This is followed by the numeric parameter ID. Next, the meanings of the unit and subunit fields are provided, if applicable. and finally the parameter data format and a reference to the appropriate table defining the parameter attribute type.¶
3.5.1. GOAROUND - Go around requested
3.5.2. P-ALT - Pressure Altitude
3.5.3. T-ALT - True Altitude
3.5.4. IAS - Indicated Airspeed
3.5.5. CAS - Calibrated Airspeed
3.5.6. CASMSG - Crew Alerting System Message
3.5.7. THROTPOS - Throttle position
3.5.8. INAIR - Are we in the air (vs. on the ground)
3.5.9. BARO - Current barometric setting
3.5.10. CLTPOS - Collective Position
3.5.11. CLTPOSREQ - A/P Requested Collective Position
3.5.12. MAGHDG - Magnetic Heading
3.5.13. MAGCRS - Magnetic Course (via RNAV)
3.5.14. TRUECRS - True Course (via RNAV)
3.5.15. MAGDTK - Desired Course (via RNAV)
3.5.16. TRUEDTK - Desired course (via RNAV)
3.5.17. LAT - Current position latitude
3.5.18. LON - Current position longitude
3.5.19. RNAVALT - Altitude measured by RNAV
3.5.20. ROLL - Current degrees of roll, -18000 being being upside down towards left, 18000 being upside down to the right
3.5.21. PITCH - Current degrees of pitch, 9000 being straight up, -9000 being straight down
3.5.22. YAW - Yaw/Inclination as measured in G force
3.5.23. FUELTOT - Computed remaining fuel (divisor may be overridden by fuel type in FUELLEVLR)
3.5.24. RNAVHFOM - Horizontal Figure of Merit
3.5.25. RNAVVFOM - Vertical Figure of Merit
3.5.26. RNAVHPL - Horizontal Protection Level
3.5.27. RNAVVPL - Vertical Protection Level
3.5.28. IASRT - Indicated Airspeed Rate of Change
3.5.29. KBDSEL - Activate the named on-screen keyboard or none if empty
3.5.30. KEYPRESS - Send the FMS encoded key press to the given display
- Parameter ID: %x00.00.1d¶
- Unit Usage: Display¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using osk_key dictionary (See Table 32.)¶
Table 32, below, shows the values defined in the osk-key Dictionary. These options represent the On screen keyboard keys.¶
| Name | Value | Definition |
|---|---|---|
| 0 | %d48 | Character 0 |
| 1 | %d49 | Character 1 |
| 2 | %d50 | Character 2 |
| 3 | %d51 | Character 3 |
| 4 | %d52 | Character 4 |
| 5 | %d53 | Character 5 |
| 6 | %d54 | Character 6 |
| 7 | %d55 | Character 7 |
| 8 | %d56 | Character 8 |
| 9 | %d57 | Character 9 |
| A | %d65 | Character A |
| B | %d66 | Character B |
| C | %d67 | Character C |
| D | %d68 | Character D |
| E | %d69 | Character E |
| F | %d70 | Character F |
| G | %d71 | Character G |
| H | %d72 | Character H |
| I | %d73 | Character I |
| J | %d74 | Character J |
| K | %d75 | Character K |
| L | %d76 | Character L |
| M | %d77 | Character M |
| N | %d78 | Character N |
| O | %d79 | Character O |
| P | %d80 | Character P |
| Q | %d81 | Character Q |
| R | %d82 | Character R |
| S | %d83 | Character S |
| T | %d84 | Character T |
| U | %d85 | Character U |
| V | %d86 | Character V |
| W | %d87 | Character W |
| X | %d88 | Character X |
| Y | %d89 | Character Y |
| Z | %d90 | Character Z |
| PREV | %d60 | Previous position or < |
| NEXT | %d62 | Next position or > |
3.5.31. SURFPOS - Position of arbitrary control surface
3.5.32. SURFREQ - Requested control surface position
3.5.33. SURFTORQUE - Aerodynamic torque applied to a control surface relative to movement
3.5.34. SURFFORCE - Aerodynamic force applied to a control surface relative to movement
3.5.35. WINDSPD - Wind Speed
3.5.36. WINDBRG - True Bearing from which wind blows
3.5.37. COMFREQKHZ - Communication Frequency
3.5.38. NAVFREQKHZ - Navigation Frequency
3.5.39. COMVOL - Communication Volume (0-100)
3.5.40. NAVVOL - Communication Volume (0-100)
3.5.41. COMSQL - Communication Squelch (0-100)
3.5.42. MUX - Selected multiplexer input or output
3.5.43. ICSVOL - Intercom Volume (0-100)
3.5.44. COMSTATE - COM radio state
- Parameter ID: %x00.00.2b¶
- Unit Usage: Radio ID¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using com_state dictionary (See Table 33.)¶
Table 33, below, shows the values defined in the com-state Dictionary. These options represent the State of communication radio.¶
| Name | Value | Definition |
|---|---|---|
| IDLE | R | Ready to Receive (Idle) |
| RX | r | Active receiving |
| TX | T | Active transmitting |
| STUCK | S | Stuck Mic |
| FAULT | F | Fault |
3.5.45. ICSRXCOMS - Which COM Radios to Monitor (mask)
3.5.46. ICSRXNAVS - Which NAV Radios to Monitor (mask)
3.5.47. ICSMODE - Intercom Mode
- Parameter ID: %x00.00.2e¶
- Unit Usage: None¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using ics_mode dictionary (See Table 34.)¶
Table 34, below, shows the values defined in the ics-mode Dictionary. These options represent the State of intercom system.¶
| Name | Value | Definition |
|---|---|---|
| PILOT | P | Pilot Isolate |
| CREW | C | Crew Isolate |
| ALL | A | All |
| FEATUREMASK | %xff.00 | Mask for intercom features |
| POSITIONAL | %x01.00 | Positional dynamic audio |
3.5.48. ICSTXCOMS - Which COM Radios to Transmit (mask)
3.5.49. DATE - Date in YYYY-MM-DD format
3.5.50. GLOAD - Current Normal to Aircraft Loading
3.5.51. RATEOFTURN - Turn Coordinator Rate Per Second
3.5.52. GROUNDSPEED - Groundspeed
3.5.53. VSPEED - Vertical speed
3.5.54. XPDRIDENT - XPDR Ident request (USERSELECT only). Non-standby transponders must IDENT regardless of UNIT. Used only to request IDENT, but IDENT state reported in XPDRMODE
3.5.55. XPDRRPS - XPDR Replies per second (normalized)
3.5.56. XPDRSQUAWK - XPDR Squawk as decimal integer (e.g., 1200). All transponders must change SQUAWK regardless of UNIT
3.5.57. XPDRMODE - XPDR Mode. Note that IDENT flag is ignored in USERSELECT condition.
- Parameter ID: %x00.00.38¶
- Unit Usage: XPDR ID¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using xpdr_mode dictionary (See Table 35.)¶
Table 35, below, shows the values defined in the xpdr-mode Dictionary. These options represent the Transponder mode and flags.¶
| Name | Value | Definition |
|---|---|---|
| UNKNOWN | %d0 | Unknown |
| MODEMASK | %x7f | Mask for mode |
| STANDBY | O | Standby |
| GND | G | On Ground |
| AIR | A | Air/Altitude Reporting |
| FLAG-IDENT | %x80 | IDENT Active |
3.5.58. NAVOBS - NAV OBS Value
3.5.59. NAVBRG - Bearing to nav aid
3.5.60. NAVCDI - Course Deviation (-1000 to 1000)
3.5.61. NAVGSI - Glide Slope (-1000 to 1000)
3.5.62. NAVFLAGS - Navigation Flags (see XFS_NAV_FLAG_*
- Parameter ID: %x00.00.3d¶
- Unit Usage: Radio/FMS ID¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using nav_flag dictionary (See Table 36.)¶
Table 36, below, shows the values defined in the nav-flag Dictionary. These options represent the Navigational flag states.¶
3.5.63. FLAPREQ - Requested Flap Position 0 = up, 100000 = fully down, -100000 is fully negative
3.5.64. FLAPPOS - Flap actuator position, 0 = up, 100000 = fully down, -100000 is fully negative
3.5.65. ECBSTAT - ECB Status change or request, see xfs_ecb.h
3.5.66. PTRIMREQ - Requested Pitch Trim Position (negative nose down, 0 neutral, positive nose up)
3.5.67. PTRIMPOS - Pitch Trim Position (negative nose down, 0 neutral, positive nose up)
3.5.68. RTRIMREQ - Requested Roll Trim Position (negative left bank, 0 neutral, positive right bank)
3.5.69. RTRIMPOS - Roll Trim Position (negative left bank, 0 neutral, positive right bank)
3.5.70. BUSSTAT - Status of Bus
3.5.71. TEMP - Arbitrary Temperature in a location
3.5.72. TAS - True Airspeed
3.5.73. TAT - Total Air Temperature
3.5.74. OAT - Outside Air Temperature accounting for compressibility
3.5.75. D-ALT - Density Altitude
3.5.76. OILPRES - Oil Pressure
3.5.77. OILTEMP - Oil Temp
3.5.78. XFDFPS - XFD Display Frames Per Second (FPS)
3.5.79. TIREPRES - Tire Pressure
3.5.80. CHT - Cylinder Head Temperature
3.5.81. EGT - Exhaust Gas Temperature
3.5.82. COOLTEMP - Coolant Temperature
3.5.83. FUELFLOW - Fuel Flow
3.5.84. FUELPRES - Fuel Pressure
3.5.85. FUELLEVL - Fuel Level (divisor may be overridden by fuel type)
3.5.86. MANPRES - Manifold pressure
3.5.87. ENGRPM - Engine RPM
3.5.88. PROPRPM - Propeller RPM
3.5.89. MACH - Mach
3.5.90. IASBUG - Target indicated airspeed
3.5.91. HDGBUG - Bugged Magnetic Heading
3.5.92. ALTBUG - Bugged Altitude
3.5.93. WAYPOINT - A waypoint in a flight plan, subunit is the position in flightplan, beginning with 1 for the first waypoint. Subunit 0 is only used to indicate an empty flight plan.
3.5.94. INSERT - Insert a waypoint in a flight plan, subunit is the position in flightplan which it should become (SYSSEL/USERSEL ONLY)
3.5.95. DELETE - Delete a waypoint in a flight plan, subunit is the position in flightplan starting at 1 (SYSSEL/USERSEL ONLY). Label must match
3.5.96. NOTE - Notation of something important within the quick access log or bus
3.5.97. NAVGPS - GPS Mode
- Parameter ID: %x00.00.60¶
- Unit Usage: NAV radio unit or FMS Unit Number¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using nav_gps dictionary (See Table 37.)¶
Table 37, below, shows the values defined in the nav-gps Dictionary. These options represent the Global positioning system status.¶
3.5.98. NAVDIS - Distance to next or last waypoint or DME for VOR/ILS/etc
3.5.99. NAVXTK - Cross track error (negative is left)
3.5.100. NAVETE - Time to next or last waypoint
3.5.101. BRIGHTNESS - Universal display brightness (0-1000 for night time mode, 1000-2000 for daytime modes
3.5.102. MANTEMP - Manifold temperature
3.5.103. DIRECT - Go direct to a waypoint in a flight plan, subunit is the position in flightplan starting at 1 (SYSSEL/USERSEL ONLY). Label must match
3.5.104. ACTIVATE - Activate leg terminating at waypoint in a flight plan, subunit is the position in flightplan (SYSSEL/USERSEL ONLY). Label must match
3.5.105. MMPARAM - Moving Map parameters. Subunit is one of XFS_MM_PARAM_*
3.5.106. SERVOREQ - Requested servo position and state
3.5.107. SERVOPOS - Current servo actuator position
3.5.108. SONICHAT - Ultrasonic rangefinder height above terrain
3.5.109. LIDARHAT - LIDAR rangefinder height above terrain
3.5.110. RADARHAT - Radar rangefinder height above terrain
3.5.111. HAT - Computed height above terrain
3.5.112. COMSTANDBY - Standby COM Frequency (same rules and range as COMFREQKHZ)
3.5.113. NAVSTANDBY - Standby NAV Frequency (same rules and range as NAVFREQKHZ)
3.5.114. STALLSPEED - Estimated real-time Stall speed
3.5.115. TIMEMS - Time in milliseconds from midnight zulu time
3.5.116. YTRIMREQ - Requested Yaw Trim Position (negative left, 0 neutral, positive right)
3.5.117. YTRIMPOS - Yaw Trim Position (negative left, 0 neutral, positive right)
3.5.118. VSPEEDBUG - Vertical speed bug in fpm
3.5.119. MUSICSRC - Music Source (0 = none)
3.5.120. AOA - Angle of attack as an actual angle
3.5.121. AOAR - Angle of attack range -- should contain green (beginning of approach range), white (reference angle), yellow (approaching stall) and a red (imminent stall)
3.5.122. GPIO - GPIO Input/Output
3.5.123. ANALOG - Raw Analog value 0-4095
3.5.124. PWM - PWM value 0-4095 -- subunit is port number, 1-8
3.5.125. XPDRACID - ICAO 24-bit Aircraft Identifier
3.5.126. XPDRFLID - Up to 8-character, NULL terminated flight ID
3.5.127. THROTREQ - Requested throttle position
3.5.128. RPMREQ - Prop governor requested RPM
3.5.129. TACHTIME - Tachometer time, unit is engine
3.5.130. TOTTIME - Total aircraft time
3.5.131. APPSTAT - Application Status / Requests
3.5.132. CDINAVSRC - Select index (> 0) of CDI NAV Source or 0 for none
3.5.133. BRGNAVSRC - Select index (> 0) CDI BRG Source or 0 for none
3.5.134. COMSEL - Select COM Radio for Tuning
3.5.135. NAVSEL - Select NAV Radio for Tuning
3.5.136. MSTRCAUTN - Master Caution Active when true. Resets by SYSSEL/USERSEL with value of FALSE
3.5.137. MSTRWARN - Master Warning Active when true. Resets by SYSSEL/USERSEL with value of FALSE
3.5.138. ROLLRT - Rate of change of about A/C longitudinal axis (P)
3.5.139. PITCHRT - Rate of change about A/C transverse axis (Q)
3.5.140. YAWRT - Rate of change about A/C vertical axis (R)
3.5.141. STKPITCH - Stick Pitch Position (negative nose down, 0 neutral, positive nose up)
3.5.142. STKROLL - Stick Roll Position (negative left bank, 0 neutral, positive right bank)
3.5.143. STKYAW - Pedal Yaw Position (negative left, 0 neutral, positive right)
3.5.144. BATTTEMP - Battery Temp
3.5.145. MOTORTEMP - Motor Temp
3.5.146. POWERTEMP - Temp of a device supplying/converting power to a propulsion system
3.5.147. TORQUE - Torque
3.5.148. TAILNUM - Up to 8-character, NULL terminated tail number
3.5.149. ROLLREQ - F/D requested degrees of roll in 100 * degrees with 0 being right side up, -18000 being being upside down towards left, 18000 being upside down to the right
3.5.150. PITCHREQ - F/D requested degrees of pitch in 100 * degrees with 0 being straight ahead, 9000 being straight up, -9000 being straight down
3.5.151. YAWREQ - F/D requested G force of inclination with 0 being no yaw
3.5.152. STKPITCHREQ - A/P Requested Stick Pitch Position (negative nose down, 0 neutral, positive nose up)
3.5.153. STKROLLREQ - A/P Requested Stick Roll Position (negative left bank, 0 neutral, positive right bank)
3.5.154. STKYAWREQ - A/P Requested Pedal Yaw Position (negative left, 0 neutral, positive right)
3.5.155. FDMODEACT - Active Flight Director Modes
- Parameter ID: %x00.00.99¶
- Unit Usage: FD Number (0 for setting values)¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using afcs_fd_mode dictionary (See Table 38.)¶
Table 38, below, shows the values defined in the afcs-fd-mode Dictionary. These options represent the Vertical, lateral and yaw modes of flight director.¶
| Name | Value | Definition |
|---|---|---|
| VERT-MASK | %xff | Vertical modes mask |
| LAT-MASK | %xff.00 | Lateral modes mask |
| YAW-MASK | %xff.00.00.00 | Yaw modes mask |
| PITCH | %x01 | Activate pitch mode |
| VS | %x02 | Activate vertical speed mode |
| FLC | %x04 | Activate indicated airspeed mode / flight level change |
| PRF | %x08 | Activate angle of attack / performance mode |
| ALT | %x10 | Arm Altitude mode |
| VNAV | %x20 | Arm vertical nav mode |
| GP | %x40 | Arm approach mode vertical portion |
| FLARE | %x80 | Arm flare mode |
| ROLL | %x01.00 | Activate wing leveler mode |
| HDG | %x02.00 | Activate heading mode |
| NAV | %x04.00 | Arm navigation mode |
| APPR | %x08.00 | Arm approach mode |
| YD | %x01.00.00.00 | Fixed Yaw Damper |
| SLIP | %x02.00.00.00 | Activate slip mode (adjustable YD) |
| SLIPAPPR | %x04.00.00.00 | Activate approach slip mode (adjustable YD) |
3.5.156. FDMODEARM - Armed Flight Director Modes (XFS_AFCS_FD_MODE_*
3.5.157. ALTHOLDBUG - Altitude used by FD for altitude hold
3.5.158. APMODE - Autopilot Modes
- Parameter ID: %x00.00.9c¶
- Unit Usage: AP Number (0 for setting value)¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using afcs_ap_mode dictionary (See Table 39.)¶
Table 39, below, shows the values defined in the afcs-ap-mode Dictionary. These options represent the Vertical, lateral and yaw modes of autopilot and throttle.¶
| Name | Value | Definition |
|---|---|---|
| VERT-MASK | %xff | Vertical modes mask |
| LAT-MASK | %xff.00 | Lateral modes mask |
| THROT-MASK | %xff.00.00 | Throttle modes mask |
| YAW-MASK | %xff.00.00.00 | Yaw modes mask |
| PITCH | %x01 | Pitch mode |
| EPPITCH | %x02 | Pitch mode only for envelope protection |
| ROLL | %x01.00 | Roll mode |
| EPROLL | %x02.00 | Roll mode only for envelope protection |
| SPD | %x01.00.00 | Activate autothrottle speed tracking |
| EPSPD | %x02.00.00 | Autothrottle only for envelope protection (SPD mode) |
| AOA | %x04.00.00 | Activate autothrottle AoA tracking |
| EPAOA | %x08.00.00 | Autothrottle only for envelope protection (AOA mode) |
| TOGA | %x10.00.00 | Activate takeoff / go-around throttle |
| EPTOGA | %x20.00.00 | Autothrottle only for envelope protection (TOGA mode) |
| YAW | %x01.00.00.00 | Yaw mode |
| EPYAW | %x02.00.00.00 | Yaw envelope protection |
3.5.159. ICSSQL - Intercom Squelch (0-100)
3.5.160. PITCHBUG - Target pitch
3.5.161. PTSPEED - Power Turbine Speed (commonly N1)
3.5.162. GTSPEED - Gas Turbine Speed (commonly N2 or Ng)
3.5.163. TIT - Turbine Inlet Temperature
3.5.164. ITT - Inter-Turbine Temperature
3.5.165. POWER - Power under current engine and environmental conditions relative to engine design maximum
3.5.166. ENGSTATUS - Engine specific set of flags or values
3.5.167. CABINALT - Cabin Equivalent Altitude
3.5.168. CABINALTREQ - Cabin Equivalent Altitude
3.5.169. DIFFPRES - Differential Pressure
3.5.170. DIFFPRESREQ - Requested Differential Pressure
3.5.171. FUELTEMP - Arbitrary Temperature in a location
3.5.172. ENGSTATE - Engine operating state
- Parameter ID: %x00.00.aa¶
- Unit Usage: Motor/Engine¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using engstate dictionary (See Table 40.)¶
Table 40, below, shows the values defined in the engstate Dictionary. These options represent the States of engines.¶
| Name | Value | Definition |
|---|---|---|
| UNKNOWN | %x00 | Engine Status Unknown |
| OFF | %x01 | Engine is Off |
| DRYMOTOR | %x02 | Engine Starting |
| STARTING | %x03 | Engine Starting |
| RUNNING | %x04 | Engine Running Normally |
| FLAMEOUT | %x05 | Engine Flamed Out / Failure |
| SHUTDOWN | %x06 | Engine Shutting Down |
| SHUTOFF | %x07 | Engine Shut Off |
| MODE-MASK | %xff | Mask for Engine State |
| FLAG-IGNITION | %x01.00 | Ignition On |
| FLAG-FUEL | %x02.00 | Fuel Shutoff Open |
| FLAG-STARTER | %x04.00 | Starter On |
| FLAG-GENERATOR | %x08.00 | Generator On |
| FLAG-BLEED | %x10.00 | Bleed Air On |
| FLAG-FIRE | %x01.00.00 | Fire Present |
| FLAG-EXTINGUISH | %x02.00.00 | Extinguisher Dispensed |
3.5.173. ENGSTATEREQ - Requested Engine operating state
3.5.174. BLEEDAIR - Bleed Air Level (Percent of Max)
3.5.175. BLEEDAIRREQ - Requested Bleed Air Level
3.5.176. LIGHTING - Lighting Color/Level
3.5.177. LIGHTINGREQ - Requested Lighting Color/Level
3.5.178. ICING - Deicing State
- Parameter ID: %x00.00.b0¶
- Unit Usage: System/0=Aircraft¶
- SubUnit Usage: Specific¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using icing_flag dictionary (See Table 41.)¶
Table 41, below, shows the values defined in the icing-flag Dictionary. These options represent the Status of ice detection, anti-ice and deicing systems.¶
| Name | Value | Definition |
|---|---|---|
| ENGINE | %x01 | Engine Deicing/Anticing On |
| AIRFRAME | %x02 | Airframe Deicing/Anticing On |
| INSEP | %x04 | Inertial Separator Activated |
| PITOT | %x08 | Pitot/Static Heat Activated |
| PROPHEAT | %x10 | Propeller Heat Activated |
| WINDHEAT | %x20 | Windshield Heat Activated |
| CARBHEAT | %x40 | Carb Heat Activated |
| CARBICEDET | %x40.00 | Carb Icing Detected |
| ICEDET | %x80.00 | Icing Detected |
| ENGINE-FAIL | %x01.00.00 | Engine Deicing/Anticing Failed |
| AIRFRAME-FAIL | %x02.00.00 | Airframe Deicing/Anticing Failed |
| INSEP-FAIL | %x04.00.00 | Inertial Separator Failed |
| PITOT-FAIL | %x08.00.00 | Pitot/Static Heat Failed |
| PROPHEAT-FAIL | %x10.00.00 | Propeller Heat Failed |
| WINDHEAT-FAIL | %x20.00.00 | Windshield Heat Failed |
| CARBHEAT-FAIL | %x40.00.00 | Carb Heat Failed |
| CARBICEDET-FAIL | %x40.00.00.00 | Carb Icing Detection Failed |
| ICEDET-FAIL | %x80.00.00.00 | Icing Detection Failed |
3.5.179. ICINGREQ - Requested Deicing State
3.5.180. LDGGEAR - Landing Gear State
- Parameter ID: %x00.00.b2¶
- Unit Usage: Wheel/0=Aircraft¶
- SubUnit Usage: Specific¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using ldggear dictionary (See Table 42.)¶
Table 42, below, shows the values defined in the ldggear Dictionary. These options represent the Status of retractable landing gear.¶
| Name | Value | Definition |
|---|---|---|
| UNKNOWN | %x00.00 | Gear Status Unknown |
| DOWN | %x00.01 | Landing Gear Down |
| UP | %x80.00 | Landing Gear Up |
| FLAG-FAILED | %x01.00.00 | Landing Gear System is Failed |
3.5.181. LDGGEARREQ - Landing Gear State
3.5.182. CABINTEMP - Cabin Temperature in a zone
3.5.183. CABINTEMPREQ - Requested Cabin Temperature in a zone
3.5.184. CHKLIST - Checklist Item
3.5.185. WBRANGE - Weight and envelope per configuration
3.5.186. WBSTARM - Arm for given station
3.5.187. WBSTMAXWEIGHT - Maximum weight at given station
3.5.188. WBSTFLAGS - Flags about given station
- Parameter ID: %x00.00.ba¶
- Unit Usage: Configuration¶
- SubUnit Usage: Station /0=total /1=total no fuel¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using station_flag dictionary (See Table 43.)¶
Table 43, below, shows the values defined in the station-flag Dictionary. These options represent the Weight and balance station types.¶
| Name | Value | Definition |
|---|---|---|
| FUEL | %x01 | This station is a fuel tank. Its weight will be in XFS_PARAM_FUELLEVL |
| HULL | %x02 | This station corresponds to the basic empty aircraft |
| FIXED | %x04 | This station's weight is not adjustable |
| PASSENGER | %x08 | This station corresponds to a passenger location |
| BAGGAGE | %x10 | This station corresponds to a baggage location |
3.5.189. WBSTWEIGHT - Actual weight at given station
3.5.190. TASEFF - Fuel Economy Relative to True Airspeed
3.5.191. GSEFF - Fuel Economy Relative to Groundspeed
3.5.192. TIMETOEMPTY - Time to Empty
3.5.193. DISTTOEMPTY - Distance to Empty
3.5.194. FLIGHTSTATE - State of Flight
- Parameter ID: %x00.00.c0¶
- Unit Usage: None¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using flight_state dictionary (See Table 44.)¶
Table 44, below, shows the values defined in the flight-state Dictionary. These options represent the Status of aircraft within flight profile.¶
| Name | Value | Definition |
|---|---|---|
| UNKNOWN | %d0 | The state of the aircraft is not known |
| OFF | %d1 | The aircraft is completely powered down |
| HIBERNATE | %d2 | Minimal aircraft systems online not visible to the pilot |
| PREFLIGHT | %d3 | Minimal aircraft systems for pilot interaction online |
| ENGINE-START | %d4 | Engine(s) are preparing to start or are starting |
| PRETAXI | %d5 | Engine(s) are started, awaiting pre-taxi items |
| TAXI | %d6 | Aircraft is ready or in process of taxiing |
| RUNUP | %d7 | Aircraft is ready for, or in process of performing runup |
| READY | %d8 | Aircraft is ready for and positioned just short of takeoff |
| TAKEOFF | %d9 | Aircraft is in process of performing takeoff |
| AFTER-TAKEOFF | %d10 | Aircraft is airborne immediately but not yet configured for normal climb |
| DEPARTURE | %d11 | Aircraft is on a standard instrument departure |
| CLIMB | %d12 | Aircraft is climbing but not on an instrument departure |
| CRUISE | %d13 | Aircraft is at final cruise |
| DESCENT | %d14 | Aircraft is descending not on a standard arrival |
| ARRIVAL | %d15 | Aircraft is on a standard arrival |
| APPROACH | %d16 | Aircraft is on an instrument approach procedure |
| VISUAL | %d17 | Aircraft is flying a visual traffic pattern |
| MISSED | %d18 | Aircraft is executing a missed approach |
| SHUTDOWN | %d19 | Aircraft engines are shutting down or have shut down |
| SECURE | %d20 | Aircraft systems are shutting down or reconfiguring for preflight |
3.5.195. UPDATESTATE - Status of any update
3.5.196. TORQUEREQ - Requested Torque
3.5.197. STKPITCHFRCE - Stick Pitch Force applied by the pilot, positive value - push, negative value - pull
3.5.198. STKROLLFRCE - Stick Roll Force applied by the pilot, positive value - roll right, negative value - roll left
3.5.199. STKYAWFRCE - Pedal Yaw Force applied by the pilot, positive value - right rudder, negative value - left rudder
3.5.200. APPITCHFRCE - Auto Pilot Pitch Force exerted on control surfaces, positive value - push, negative value - pull
3.5.201. APROLLFRCE - Auto Pilot Roll Force exerted on control surfaces, positive value - roll right, negative value - roll left
3.5.202. APYAWFRCE - Auto Pilot Yaw Force exerted on control surfaces, positive value - right rudder, negative value - left rudder
3.5.203. EFBPARAM - Up to 64-character, NULL terminated parameter value
3.5.204. OILPRESCOMP - Compensated Oil Pressure
3.5.205. MACHBUG - Target Mach
3.5.206. AOART - Angle of attack rate of change
3.5.207. TASBUG - Target true airspeed
3.5.208. GSBUG - Target groundspeed
3.5.209. AOABUG - Bugged AOA
3.5.210. ECUTIME - ECU Hours
3.5.211. DBASE - Active database information
3.5.212. EAS - Equivalent Airspeed
3.5.213. EASRT - Equivalent Airspeed Rate of Change
3.5.214. EASBUG - Target equivalent airspeed
3.5.215. POWERREQ - Requested power as percent of engine design maximum
3.5.216. BRAKE - Wheel brake status
- Parameter ID: %x00.00.d7¶
- Unit Usage: Left=1,Right=2,No direction=0¶
- SubUnit Usage: Specific¶
- Format: UINT (See Table 8.)¶
- Range: parameter MUST NOT be sent with a range attribute.¶
- Values interpreted using brake dictionary (See Table 45.)¶
Table 45, below, shows the values defined in the brake Dictionary. These options represent the Status of wheel brakes.¶
| Name | Value | Definition |
|---|---|---|
| UNKNOWN | %x00.00 | Brake Status Unknown |
| NONE | %x00.01 | Brakes not pressed |
| MAX | %x80.00 | Max Braking |
| PARK | %x01.00.00 | Parking Brake Engaged |
| FLAG-FAILED | %x02.00.00 | Brake System is Failed |
3.5.217. BRAKEREQ - Amount of brake requested
3.5.218. NAVSQL - Communication Squelch (0-100)
3.5.219. STATIONID - VOR Station ID decoded from Morse code
3.5.220. SVPARAM - Synthetic Vision parameters. Subunit is one of XFS_SV_PARAM_*
3.5.221. FDCDISEL - Global selection of which CDI the flight director should track
3.5.222. BLOODOXY - Blood oxygen level of given seat occupant
3.5.223. PULSE - Pulse rate of given seat occupant
3.5.224. BREATHS - Breathing rate of given seat occupant
3.5.225. CARBMONOX - Carbon Monoxide levels detected by sensor
3.5.226. FLOWRATE - Oxygen flow rate
3.5.227. TANKPRES - Oxygen tank pressure
3.5.228. RNAVVS - Vertical speed computed from RNAV
3.5.229. COMPRESET - Selected COM Radio Preset (0=Non-preset frequency)
- Parameter ID: %x00.00.e4¶
- Unit Usage: Radio¶
- SubUnit Usage: None¶
- Format: UINT (See Table 8.)¶
- Range: parameter MAY be sent with a range attribute.¶
- Values interpreted using preset dictionary (See Table 46.)¶
Table 46, below, shows the values defined in the preset Dictionary. These options represent the XSEDE Preset Frequency.¶
| Name | Value | Definition |
|---|---|---|
| MANUAL | %d0 | Manual Tuning (no preset) |
| LAST | %xff.fe | Last selected frequency |
3.5.230. COMNAME - Name of COM Radio or Preset Frequency
3.5.231. NAVPRESET - Selected NAV Radio Preset (0=Non-preset frequency)
3.5.232. NAVNAME - Name of NAV Radio or Preset Frequency
3.5.233. VNORTH - North component of velocity in true world coordinates
3.5.234. VEAST - East component of velocity in true world coordinates
3.5.235. ENGPOWER - Current Engine Power
3.5.236. CHARGE - Measured remaining battery charge
3.5.237. CHARGETOT - Computed remaining charge
4. Message Transport
4.1. Message Composition
Application software on a node determines when information or raw data need to be sent onto the network. These transmissions are done as messages with raw data and messages with parameters. If subsequent information or raw data having the same message class, ID, and flags occur in a timely fashion, they MAY be coalesced into a single message.¶
For each parameter to be sent, the common header (See Section 3.2) the common data items MUST be populated. In addition, the Ident and Parameter Data MUST be populated with the corresponding data as per Section 3.5. The length in the common header MUST represent the actual length of the data, however, the parameter must be padded to a size that is a multiple of four octets.¶
The message header MUST be populated with the corresponding data as per Section 3.1, the message number MUST be monotonically increasing with an arbitrary initial value, and then the length in the common header MUST be set equal to the sum of the padded parameter length values. Once this assembly process is complete, the message may be transmitted.¶
4.2. Message Signing
Body text¶
4.3. Message Transmission and Reliability
XSEDE is designed to be used with a broadcast UDP protocol however, there is no requirement to do so. Each endpoint MUST specify a listening address and port number with the default being 224.0.2.69 on port 20234. The actual address and port number are to be chosen by the system designer / installer for their particular needs. [RFC5771] specifies IPv4 Multicast Address Assignments and SHOULD be followed.¶
If the XSEDE message is successfully transmitted, no further action is required.¶
4.4. Message Reception & decoding
XSEDE messages are received on the address and port that was configured in the prior section. Upon receiving a message, the src id and message number MUST be examined to ensure that this message is neither out of order nor a duplicate: Since lower level network tolopogies may affect the potential for packet delay and retransmission, each node MUST maintain a message look-back window size setting, default 4. Each node MUST also record of the last message number received from a node. If a subsequent message number is received out of order andis within the look back window, the message MUST be discarded. Otherwise, the message is a valid message. This arrangement accounts for both integer overflows and node restarts. Then, if the message is considered valid, each XSEDE node MUST examine each parameter in the XSEDE message to determine if it requires local processing. Local processing is beyond the scope of this document.¶
Since there is no assured message delivery, all parameter interpretations MUST be idempotent to ensure multiple interpretations, or execution results in the same outcome.¶
4.5. Message Signing
Since XSEDE operates on a closed network, message signing is not currently supported but may be added in the future.¶
5. Example Message Flows
This section illustrates XSEDE features by example. The first example controls the radio.¶
5.1. Adjust radio
This example sets the radio Set Radio frequency and squelch by broadcasting USERSEL parameters. If a node controlling the radio receives the request, it will respond with a result similar to the one shown afterwards.¶
5.1.1. Message Header
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| src id | message number |
| 1001 | 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg class | message ID | flags |
| 3 = OP | FLIGHTDATA 2 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| tcid | len |
| NONE 0 | %x10 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
- src id:
- UINT16; This value was set to 1001 decimal at installation time.¶
- message number:
- UINT16; 20 decimal for illustration purposes.¶
- msg class:
- UINT8; "OP" value 3 decimal.¶
- message ID:
- UINT8; FLIGHTDATA decimal 2¶
- flags:
- UINT16; LEVEL-A decimal 5; See Table 3.¶
- tcid:
- t-NONE; See Table 4.¶
- len:
- UINT16 ; 0x10, or decimal 16 bytes.¶
5.1.2. Frequency Message Header
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 2 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | COMFREQKHZ %x00.00.24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | USERSEL 192 | %x00 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 122750 or 0x0001 df7e |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- Unit:
- UINT16; decimal 2 to match the requested radio.¶
- SubUnit:
- UINT16; 0 to signify the radio itself.¶
- Parameter Data Len:
- 11 bits; decimal 4.¶
- Ident:
- 21 bits; COMFREQKHZ - Communication Frequency, value %x00.00.24 See Section 3.5.¶
- Format:
- UINT (OCTET): decimal 2. See Section 3.3.¶
- Confidence:
- decimal 192 (OCTET): USERSEL. See Table 5.¶
- Expire:
- OCTET; Time to live. %x00 to not expire. See Section 3.2.2 for encoding.¶
- Pflags:
- LEVEL-A (OCTET) decimal 5. See Table 3¶
- Parameter Data:
- *(OCTET) value would be 122750, 0x0001 df7e.¶
5.1.3. Squelch Message Header
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 2 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | COMSQL %x00.00.28 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | USERSEL 192 | %x00 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 53 or 0x0000 0035 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- Unit:
- UINT16; decimal 2 to match the requested radio.¶
- SubUnit:
- UINT16; 0 to signify the radio itself.¶
- Parameter Data Len:
- 11 bits; decimal 4.¶
- Ident:
- 21 bits; COMSQL - Communication Squelch (0-100), value %x00.00.28 See Section 3.5.¶
- Format:
- UINT (OCTET): decimal 2. See Section 3.3.¶
- Confidence:
- decimal 192 (OCTET): USERSEL. See Table 5.¶
- Expire:
- OCTET; Time to live. %x00 to not expire. See Section 3.2.2 for encoding.¶
- Pflags:
- LEVEL-A (OCTET) decimal 5. See Table 3¶
- Parameter Data:
- *(OCTET) value would be 53, 0x0000 0035.¶
5.1.4. Radio Status Report
After the above parameters affect a change in the radio, or as part of the radio's regularly scheduled parameter broadcast, a message like the following will be transmitted. It has almost all the same values as the original message but would likely include other parameters as well. Only the changed parameters are described.¶
The expire time is chosen at 2-3 times the scheduled broadcast time to ensure a fresh message is received within the valid time period should one be lost.¶
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| src id | message number |
| 1777 | 1255 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg class | message ID | flags |
| 3 = OP | FLIGHTDATA 2 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| tcid | len |
| NONE 0 | %x20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 2 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | COMFREQKHZ %x00.00.24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | RAW / R 10 | %xC9 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 122750 or 0x0001 df7e |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 2 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | COMSQL %x00.00.28 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | RAW / R 10 | %xC9 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 53 or 0x0000 0035 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
- src id:
- UINT16; This value is different than the prior message because this message is sent by the node controlling the radio. It was set to 1777 decimal at installation time.¶
- message number:
- UINT16; decimal 1255 for illustrative purposes. Note: this value is the current message sequence number for node 1777.¶
- Confidence:
- decimal 10 (OCTET): RAW / REPORTED in both parameters since this value is the actual reported value from the device. See Table 5.¶
- Expire:
- OCTET; Time to live. %xC9 to expire in about 15 seconds. See Section 3.2.2 for encoding.¶
5.2. Deploy Landing Gear Example
Landing Gear changes are different than radio changes in that it may take several seconds to affect a change. In this scenario, we will see a report by the node controlling the landing gear, followed by a parameter showing the user selecting a new value. Next, there will be a series of parameter broadcasts that showing the gear moving into position.¶
5.2.1. Initial Gear State Message
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| src id | message number |
| 2222 | 3400 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg class | message ID | flags |
| 3 = OP | FLIGHTDATA 2 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| tcid | len |
| NONE 0 | %x20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 1 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | LDGGEAR %x00.00.b2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | RAW / R 10 | %x77 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 0x8000 - up. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 2 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | LDGGEAR %x00.00.b2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | RAW / R 10 | %x77 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 0x8000 - up. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Above we see a periodic message indicating that each of the two landing gear are in an up position. If these were the only two landing gear, an alternative representation would be to send a single parameter with a a unit of zero to indicate all gear is in an up position. The attributes of the message are as follows:¶
- src id:
- UINT16; This value was set to 2222 decimal at installation time.¶
- message number:
- UINT16; 3400 decimal for illustration purposes.¶
- msg class:
- UINT8; "OP" value 3 decimal.¶
- message ID:
- UINT8; FLIGHTDATA decimal 2¶
- flags:
- UINT16; LEVEL-A decimal 5; See Table 3.¶
- tcid:
- t-NONE; See Table 4.¶
- len:
- UINT16 ; 0x20 bytes.¶
- Parameter (First):
-
- Unit:
- UINT16; Decimal 1 for landing gear unit 1¶
- SubUnit:
- UINT16; 0¶
- Parameter Data Len:
- 11 bits; decimal 4.¶
- Ident:
- 21 bits; LDGGEAR - Landing Gear State, value %x00.00.b2 See Section 3.5.¶
- Format:
- UINT (OCTET): decimal 2. See Section 3.3.¶
- Confidence:
- decimal 10 (OCTET): RAW. It is the value reported by the actuator. See Table 5.¶
- Expire:
- OCTET; Time to live. %x77 to expire in 2.9 seconds. See Section 3.2.2 for encoding.¶
- Pflags:
- LEVEL-A (OCTET) decimal 5. See Table 3¶
- Parameter Data:
- *(OCTET) value is 0x8000.¶
- Parameter (Second):
-
- Unit:
- UINT16; Decimal 2 for landing gear unit 2¶
- SubUnit:
- UINT16; 0¶
- Parameter Data Len:
- 11 bits; decimal 4.¶
- Ident:
- 21 bits; LDGGEAR - Landing Gear State, value %x00.00.b2 See Section 3.5.¶
- Format:
- UINT (OCTET): decimal 2. See Section 3.3.¶
- Confidence:
- decimal 10 (OCTET): RAW. It is the value reported by the actuator. See Table 5.¶
- Expire:
- OCTET; Time to live. %x77 to expire in 2.9 seconds. See Section 3.2.2 for encoding.¶
- Pflags:
- LEVEL-A (OCTET) decimal 5. See Table 3¶
- Parameter Data:
- *(OCTET) value is 0x8000.¶
5.2.2. Gear Position Request
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| src id | message number |
| 1001 | 2001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg class | message ID | flags |
| 3 = OP | FLIGHTDATA 2 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| tcid | len |
| NONE 0 | %x10 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 0 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | LDGGEARREQ %x00.00.b3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | RAW / R 10 | %x00 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 0x0001, down. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Below we see an example message that could have been made by a landing gear button.¶
- src id:
- UINT16; This value was set to 1001 decimal at installation time.¶
- message number:
- UINT16; 2001 decimal for illustration purposes.¶
- msg class:
- UINT8; "OP" value 3 decimal.¶
- message ID:
- UINT8; FLIGHTDATA decimal 2¶
- flags:
- UINT16; LEVEL-A decimal 5; See Table 3.¶
- tcid:
- t-NONE; See Table 4.¶
- len:
- UINT16 ; 0x10 or 16 decimal bytes.¶
- Parameter (Only):
-
- Unit:
- UINT16; Decimal 0 for the plane's landing gear.¶
- SubUnit:
- UINT16; 0¶
- Parameter Data Len:
- 11 bits; decimal 4.¶
- Ident:
- 21 bits; LDGGEARREQ - Landing Gear State Request, value %x00.00.b3 See Section 3.5.¶
- Format:
- UINT (OCTET): decimal 2. See Section 3.3.¶
- Confidence:
- decimal 192 (OCTET): USERSEL. See Table 5.¶
- Expire:
- OCTET; Time to live. %x00 to not expire. See Section 3.2.2 for encoding.¶
- Pflags:
- LEVEL-A (OCTET) decimal 5. See Table 3¶
- Parameter Data:
- *(OCTET) 0x0001, down.¶
5.2.3. First Changed Gear State Message
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| src id | message number |
| 2222 | 3401 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg class | message ID | flags |
| 3 = OP | FLIGHTDATA 2 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| tcid | len |
| NONE 0 | %x20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 1 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | LDGGEAR %x00.00.b2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | RAW / R 10 | %x77 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 0x3901, in transit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 2 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | LDGGEAR %x00.00.b2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | RAW / R 10 | %x77 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 0x4121, in transit |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The above message was sent while the landing gear was in transit. It shows the position values for each gear to be different, but both in transit. The expiry is set to 0x77 and about 2.9 seconds as the sending node intends to send updates at least once per second. The longer time period accounting for potential losses.¶
- src id:
- UINT16; This value was set to 2222 decimal at installation time.¶
- message number:
- UINT16; 3401 decimal for illustration purposes.¶
- msg class:
- UINT8; "OP" value 3 decimal.¶
- message ID:
- UINT8; FLIGHTDATA decimal 2¶
- flags:
- UINT16; LEVEL-A decimal 5; See Table 3.¶
- tcid:
- t-NONE; See Table 4.¶
- len:
- UINT16 ; 0x20 bytes.¶
- Parameter (First):
-
- Unit:
- UINT16; Decimal 1 for landing gear unit 1¶
- SubUnit:
- UINT16; 0¶
- Parameter Data Len:
- 11 bits; decimal 4.¶
- Ident:
- 21 bits; LDGGEAR - Landing Gear State, value %x00.00.b2 See Section 3.5.¶
- Format:
- UINT (OCTET): decimal 2. See Section 3.3.¶
- Confidence:
- decimal 10 (OCTET): RAW. It is the value reported by the actuator. See Table 5.¶
- Expire:
- OCTET; Time to live. %x77 to expire in 2.9 seconds. See Section 3.2.2 for encoding.¶
- Pflags:
- LEVEL-A (OCTET) decimal 5. See Table 3¶
- Parameter Data:
- *(OCTET) value is 0x3901, in transit .¶
- Parameter (Second):
-
- Unit:
- UINT16; Decimal 2 for landing gear unit 2¶
- SubUnit:
- UINT16; 0¶
- Parameter Data Len:
- 11 bits; decimal 4.¶
- Ident:
- 21 bits; LDGGEAR - Landing Gear State, value %x00.00.b2 See Section 3.5.¶
- Format:
- UINT (OCTET): decimal 2. See Section 3.3.¶
- Confidence:
- decimal 10 (OCTET): RAW. It is the value reported by the actuator. See Table 5.¶
- Expire:
- OCTET; Time to live. %x77 to expire in 2.9 seconds. See Section 3.2.2 for encoding.¶
- Pflags:
- LEVEL-A (OCTET) decimal 5. See Table 3¶
- Parameter Data:
- *(OCTET) value is 0x4121, in transit.¶
5.2.4. Final Gear State Message
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| src id | message number |
| 2222 | 3402 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| msg class | message ID | flags |
| 3 = OP | FLIGHTDATA 2 | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| tcid | len |
| NONE 0 | %x20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 1 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | LDGGEAR %x00.00.b2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | RAW / R 10 | %xDB | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 0x0001, down. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Unit | SubUnit |
| 2 | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Data Len | Ident |
| 4 | LDGGEAR %x00.00.b2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Format | Confidence | Expire | Pflags |
| UINT 2 | RAW / R 10 | %xDB | LEVEL-A 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Parameter Data :
| 0x0001, down. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The mesage above indicates that both landing gear are down (value 0x0001) and the message expiry has increased to 0xDB, or about 59 seconds. Since the gear are now in a static position, the node only intends to send updates every 20 seconds or so following the expire a message at about three times the sending frequency. In practice, to ensure delivery the long expiry should be introduced after at least one prior notification that it reached that state.¶
- src id:
- UINT16; This value was set to 2222 decimal at installation time.¶
- message number:
- UINT16; 3402 decimal for illustration purposes.¶
- msg class:
- UINT8; "OP" value 3 decimal.¶
- message ID:
- UINT8; FLIGHTDATA decimal 2¶
- flags:
- UINT16; LEVEL-A decimal 5; See Table 3.¶
- tcid:
- t-NONE; See Table 4.¶
- len:
- UINT16 ; 0x20 bytes.¶
- Parameter (First):
-
- Unit:
- UINT16; Decimal 1 for landing gear unit 1¶
- SubUnit:
- UINT16; 0¶
- Parameter Data Len:
- 11 bits; decimal 4.¶
- Ident:
- 21 bits; LDGGEAR - Landing Gear State, value %x00.00.b2 See Section 3.5.¶
- Format:
- UINT (OCTET): decimal 2. See Section 3.3.¶
- Confidence:
- decimal 10 (OCTET): RAW. It is the value reported by the actuator. See Table 5.¶
- Expire:
- OCTET; Time to live. %x77 to expire in 2.9 seconds. See Section 3.2.2 for encoding.¶
- Pflags:
- LEVEL-A (OCTET) decimal 5. See Table 3¶
- Parameter Data:
- *(OCTET) value is 0x0001, down.¶
- Parameter (Second):
-
- Unit:
- UINT16; Decimal 2 for landing gear unit 2¶
- SubUnit:
- UINT16; 0¶
- Parameter Data Len:
- 11 bits; decimal 4.¶
- Ident:
- 21 bits; LDGGEAR - Landing Gear State, value %x00.00.b2 See Section 3.5.¶
- Format:
- UINT (OCTET): decimal 2. See Section 3.3.¶
- Confidence:
- decimal 10 (OCTET): RAW. It is the value reported by the actuator. See Table 5.¶
- Expire:
- OCTET; Time to live. %x77 to expire in 2.9 seconds. See Section 3.2.2 for encoding.¶
- Pflags:
- LEVEL-A (OCTET) decimal 5. See Table 3¶
- Parameter Data:
- *(OCTET) value is 0x0001, down.¶
6. IANA Considerations
This memo includes no request to IANA.¶
7. Security Considerations
This document should not affect the security of the Internet.¶
This protocol is currently designed to be deployed on an isolated private network. As such, message encryption, authenticity, and modification detection are not protocol priorities.¶
7.1. Interception
Message Interception is not considered a significant threat for XSEDE because there is no private data in the system.¶
7.2. Impersonation and MITM
Impersonation and Man in the Middle (MITM) are unlikely because normally the network is physically isolated and not routed to other networks. Strategies for signing messages are a future consideration.¶
7.3. Denial of Service
Due to secure installation and physical isolation, Denial of Service is not a significant concern.¶
8. References
8.1. Normative References
- [RFC0768]
- Postel, J., "User Datagram Protocol", STD 6, RFC 768, DOI 10.17487/RFC0768, , <https://www.rfc-editor.org/info/rfc768>.
- [RFC0791]
- Postel, J., "Internet Protocol", STD 5, RFC 791, DOI 10.17487/RFC0791, , <https://www.rfc-editor.org/info/rfc791>.
- [RFC2640]
- Curtin, B., "Internationalization of the File Transfer Protocol", RFC 2640, DOI 10.17487/RFC2640, , <https://www.rfc-editor.org/info/rfc2640>.
- [RFC8174]
- Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
- [IEEE8023]
- IEEE, "IEEE Standard for Ethernet", DOI 10.1109/ieeestd.2018.8457469, , <http://dx.doi.org/10.1109/ieeestd.2018.8457469>.
- [ISO88591]
- International Organization for Standardization, "Information technology -- 8-bit single-byte coded graphic character sets -- Part 1: Latin alphabet No. 1", ISO/IEC 8859-1:1998, .
- [DO-178C]
- RTCA - Radio Technical Commission for Aeronautics, "DO-178C - Software Considerations in Airborne Systems and Equipment Certification", , <https://my.rtca.org/productdetails?id=a1B36000001IcmrEAC>.
- [GLD90]
- Garmin International, Inc., "GDL 90 Data Interface Specification", , <https://www.faa.gov/air_traffic/technology/adsb/archival/media/GDL90_Public_ICD_RevA.PDF>.
8.2. Informative References
- [RFC5771]
- Cotton, M., Vegoda, L., and D. Meyer, "IANA Guidelines for IPv4 Multicast Address Assignments", BCP 51, RFC 5771, DOI 10.17487/RFC5771, , <https://www.rfc-editor.org/info/rfc5771>.
- [RFC2119]
- Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.