4
$\begingroup$

I'm a newbie in ARINC-429 standard; the following might be a very simple issue for you. In ARINC 429 the LABEL field is covered by the bits 1 through 8; which bits are covering the Equipment ID? For istance: Equipment ID 002 hex (Flight Management Computer) would require 12 bits to be represented. Where are located these bits in the ARINC word, so that the receiver could read the it? Thanks for your assistance.

$\endgroup$
4
$\begingroup$

ARINC 429 is a unidirectional one-to-many (broadcast) transfer bus with a maximum of 20 receivers.

enter image description here
Source
Design with four unidirectional ARINC 429 buses

There is normally little need to identify the source, as there is only one. So there is no field in the protocol word dedicated for ID transmission. As visible in the previous image, bidirectional exchanges require two buses and several ports to connect them. The receiving unit (LRU) can determine from the port used which source feeds the bus.

However label 377 (octal) can be used to transmit, from time to time, the equipment ID if desired. Example: ID 10D (hex):

enter image description here

Source: ARINC specifications

Note: On the other hand, SDI bits can be used by the source to select the receiver.

$\endgroup$
  • $\begingroup$ SDI - Source/Destination Identifier can be used to identify either the source or destination of multiple LRUs of the same type. Tuning controls will use it to select the destination LRU. e.g.; VOR is controlled with Label 034. SDI will indicate whether the tuning label is intended for the left or right VOR. With 3 IRS on board, they each use SDI to indicate which IRS the data originated from. This allows receiving LRUs to select a specific source IRS (Left, Center, Right) for their data. When LRUs are installed, discrete hardwired inputs set the LRU's position. $\endgroup$ – Gerry Jul 10 '17 at 0:42
  • $\begingroup$ Your answer was a big clarification of my doubt. Thank you so much, I really appreciate it. $\endgroup$ – nibbioreale Jul 10 '17 at 21:20
0
$\begingroup$

As said earlier label 377 can be sent for Eqip ID. Alternatively, if you are the source then you can reserve few data bits for equip id and have it documented in your ICD.

$\endgroup$
  • $\begingroup$ The equipment ID should only ever go in the label 377, anything else isn't going to be compatible with the receiving equipment. $\endgroup$ – selectstriker2 Jan 2 '19 at 16:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.