L3 500-4030-000 RIPS, Maintenance Manual

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COMPONENT MAINTENANCE MANUAL
AVIATION PRODUCTS
Model FA5000
Rev. 02 Page 56
July 21/17
Description and Operation
23–70 − 30
Use or disclosure of information on this sheet is subject to
the restrictions on the cover page of this document.
B. DataLink Heartbeat
In addition to providing the originating system status (e.g. CMU), the Label 270 input
word is also used for DataLink “heartbeat” detection by the CVR. A valid Label 270
input (including good parity) must be received once per second by the CVR. If this
heartbeat is not detected for 40 consecutive seconds for the three consecutive sec-
onds for the FA5000CVR, and the DataLink Valid discrete input (Pin 56) is asserted,
a DataLink Interface fault will be asserted (as reported in the Label 350 CVR Status
Word output). Likewise, a DataLink Interface fault will also be reported if the Label
270 heartbeat is detected, and DataLink Valid (Pin 56) is not asserted.
C. Williamsburg Bit − Oriented Protocol Version Support
It should be noted that the FA5000 CVR does not currently support Williamsburg
Version 1 protocol or a low speed ARINC 429 interface for input of DataLink informa-
tion.
However, the CVR does support the Williamsburg ALOHA exchange, even though it
is not required for Williamsburg Version 3 DataLink input. In the event that the CVR
receives a valid ALO input on the SAL Label 157 (or 156), it will respond with a valid
Label 304 ALR output indicating support for the Version 3 protocol.
The format of the Label 157 or 156 ALO input is as follows:
Label 157 0r 156 ALO Input
Bit No Function Status
1-8 System Address Label 157 or 156 01101111 or 01101110
9-24 Don’t Care (not used by CVR) xxxxxxxxxxxxxxxx
25-28 ALO 1110
29-31 Protocol 001
32 Parity
The format of the Label 304 ALR response word from the CVR, indicating support
for Version 3 only, is shown below.
CVR Label 304 ALR Output (in response to ALO input)
Bit No Function Status
1­8 System Address Label 304 11000100
9­12 Version Supported (3) 1100
13­24 Reserved 000000000000
25­28 ALR 0001
29­31 Protocol 001
32 Parity
As noted above, this ALOHA exchange is not necessary to initiate Williamsburg Ver-
sion 3 DataLink input to the CVR.
The document reference is online, please check the correspondence between the online documentation and the printed version.