COMPONENT MAINTENANCE MANUAL
AVIATION RECORDERS
FA2100CVR
Rev. 15 Page 68
Apr. 14/16
Description and Operation
23–70–04
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to the restrictions on the cover page of this document.
F
DataLink Valid Discrete input (Pin 56)
F
DataLink Fault Discrete output (Pin 31)
All Label 270, 276, 157, and 156 words input on the CVR DataLink interface will be
recorded to crash protected memory regardless of the parity (good or bad). Like-
wise, these inputs, if present, will be recorded regardless of the state of the DataLink
Valid discrete input (Pin 56).
A.
Data Link Input and Encapsulation
It is generally recognized that the Williamsburg Version 3 CVR input will utilize only
Command frames containing the encapsulated DataLink message information.
These Command frames then include the ARINC 619 formatting which provides the
Network layer interface. However, the FA2100CVR records data at the link layer in-
terface level and is unaffected by any link layer, or above, data content. This means
that the CVR will record all 32 bits of each and every SAL 157 or 156 word received
on the DataLink input.
As a result, the CVR will not be impacted by any changes or additions to the ap-
proved DataLink message set. Likewise, the CVR DataLink recording function is not
affected by the ARINC 619 General Format Identifier (GFI) coding or by the Exten-
ded GFI header encoding currently defined for message encapsulation. This tech-
nique provides the maximum flexibility in DataLink recording without the need for fu-
ture CVR changes as the approved message set or associated encapsulation proto-
cols continue to evolve.
A generic DataLink encapsulation structure is illustrated in Figure 2.1 below.
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