-
"at the latest" for Type 1 and 3 systems - phases 4 thru 9 a For Type 2 systems - phases 5 a thru 7a.
a The CFDIU establishes the CURRENT/LAST LEG REPORT.
_ At each scrutinization of a system input (bus or discrete), the CFDIU:
-Monitors refreshment of information transmitted on the buses on each of the ARINC 429 input ports (except those which are excluded by pin programming). Non-refreshment detection is carried out by monitoring label 356 which is permanently transmitted by the subscriber systems. Non-refreshment is confirmed in 4 seconds. Each time a non-refreshment is detected, the CFDIU associates the ATA reference and the system identity and memorizes the following external fault message:
XX - XX - XX NO XX...X DATA system ATA System identity coded REFERENCE on 9 characters max.
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CFDIU - Faults Storage "at the soonest" in CFDIU : Normal Mode
Figure 010
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CFDIU - Faults Storage "at the soonest" in CFDIU: Normal Mode
Figure 010A
R 1EFF : 106-149, 155-199, 208-299, 301-399, 1 31-32-00Page 38 1401-499, 1Aug 01/05 1 1 1CES 1
CFDIU - Faults Storage "at the latest" in CFDIU : Normal Mode
Figure 011
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Assignment is carried out with respect to the input port.
Furthermore the CFDIU carries out correlation of this
fault (see Correlation Function below).
It detects intermittent operation of the system and adds
(INTM) to the message so as to indicate that the system
operates intermittently.
Example of message:
NO XXXX...X DATA (INTM) 9 char. max.
NOTE : The CFDIU does not monitor the non-refreshment of
____ the ECB bus when it is not supplied in flight.
-Acquires the fault messages and memorizes them:
* Type 1 or 2 systems It checks the validity of the received frames (messages) prior to their memorization. The following checks are performed: . Delta Block Word Count of first Start of Text (STX) more than 0. It checks that the number of words received between the first STX and the End of Transmission (EOT) is equal to the Block Word Count of the first STX. It checks that the Block Word Count associated with the STX(s) (except the first one in the frame) is at zero. It checks that an End of Text (ETX) is always followed by an STX. In these conditions the message(s) corresponding to the Block Word count increase is(are) acquired and memorized. Increase of the Block Word Count indicates that a first or a new fault has been detected by the system. The most recent fault message (the one that caused the modification of the Block Word Count) is the first message transmitted. . Delta Block Word Count of first STX less than or equal to 0. In this case the frame is immediately rejected and the following system is selected (polling). . Character check It checks that the characters composing the messages belong to the ASCII table of the MCDU characters. It detects the nature of the fault (internal or external to the system). It memorizes the new internal fault message and it also memorizes the identity of the systems that reacted to the internal fault by transmitting an external fault within
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b
_
the 30 seconds that preceded or followed (see Correlation Function below).
* Type 3 systems On each input discrete which is associated with the identification of a system fault, it scrutinizes discrete state so as to detect the state indicating the fault. It associates and memorizes a text enabling identification of the anomaly at each change in discrete state. Example : 240000 GCU EMERG (Ref. Fig. 012) Let us suppose that an angle of attack sensor fault has been detected and that systems A, B, C and D are affected by this fault. Systems A, B, C and D transmit EXTERNAL fault information on their bus. The air data system transmits the INTERNAL fault information; this is the message memorized by the CFDIU. The CFDIU also memorizes the identity of systems A, B, C and D which reacted to the air data system fault by transmitting an external fault message (correlation).
-Assigns the time to each event: For each new or the first fault occurrence memorized by the CFDIU, the latter associates the GMT (hour and minute) at which it occurred with it. GMT is memorized with the fault identity. Example: GMT : 0920 315000 FWC1 In the event of several non-refreshments being detected in a given flight, only the GMT associated with the first occurrence is memorized (capacity : 40 lines of 24 characters).
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