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SYSTEM DESCRIPTION, INSTALLATION, AND MAINTENANCE MANUAL
Table 5-8. Availability of ARINC 429 ICAO ADDRESS (AES ID) from 429 Ports
TP10 Pin A
1
ICAO ADDRESS (AES ID) NOT AVAILABLE FROM CMU NO. 1 OR CMU NO. 2 OR
AES ID INPUT
0
ICAO ADDRESS (AES ID) IS AVAILABLE FROM CMU NO. 1 OR CMU NO. 2 OR AES
ID INPUT
(2) When wired to the zero state, the TP10A configuration pin indicates the ICAO 24--bit
aircraft address (AES ID) is available in the ARINC 429 label 275/276 format from
one or both of the SDU CMU input ports or ARINC 429 label 214/216 format from the
AES ID input port, and that one of those ARINC 429 sources of the address is used
with no specific preference for CMU 1, CMU 2, or the AES ID input. In this state, the
discrete inputs on SDU pins MP13C thru MP13K and MP14D thru MP14J are not
assumed to be wired and the SDU does not use the discretes, even if the ARINC 429
sources fail or remain inactive.
(3) In the zero state, the SDU monitors the CMU 1, CMU 2, and AES ID input buses until
a valid ICAO address is received. Bits 1 thru 16 of the AES ID are obtained from the
label 214/275 word and bits 17 thru 24 are obtained from the label 216/276 word.
The SDU only constructs a full 24-bit address from labels 214/275 and 216/276
words received from the same input port (e.g., label 214/275 from CMU 1 can not be
combined with label 216/276 from CMU 2 or label 216 from the AES ID input). The
address is only considered valid if it does not consist of all zeros or ones, and has
been received in ARINC 429 words with their sign--status matrix (SSM) indicating
normal operation.
(4) If address words containing either all zeros or ones are received, followed by address
words with a valid address (i.e., not all zeros or ones), the SDU verifies the receipt of
both labels 214/275 and 216/276 at least twice with the same address bits content in
each respective word before declaring the address valid. This is to preclude the SDU
from inadvertently and prematurely assuming the address is valid after only one of
the two labels has yielded a valid segment of the overall address, but the most
previously received copy of the other label has not yet been updated to its intended
code. The root problem is that the 24 correlated address bits are transmitted in two
separate asynchronous words that are not inherently correlated/paired. This
requirement is intended to effectively pair the label 214/275 and 216/276
transmissions.
Honeywell International Inc. Do not copy without express permission of Honeywell.
MCS--4200/7200 Multi--Channel SATCOM System
Interpretation
23- -20- -35
Page 5--59
15 Jul 2006
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