*
Transfers a primary FDCF to secondary
*
Monitors the datalink interface.
The redundancy management makes sure that one of the two FDCFs is primary and one is secondary at power-up. To do this, the primary FDCF:
*
Remembers which FDCF was primary at last power-on
*
Monitors the condition and status of the secondary FDCF.
The secondary FDCF does the same functions as the primary.
The primary-to-secondary FDCF transfer occurs when the primary FDCF fails. The secondary FDCF monitors the intercabinet status messages from the primary FDCF during normal operation. The primary FDCF uses the results of the monitors and power conditions to change to the secondary FDCF.
The secondary FDCF also takes over when a datalink interface is lost.
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DCMS -FDCF FUNCTIONAL DESCRIPTION
BITE
The FDCF BITE monitors the hardware and software of the FDCF in the left and right CPM/Comm. When the system first gets power, the power up BITE test makes sure that the FDCF works correctly. During normal operation, the BITE monitors the condition of the FDCF for redundancy management.
Airline Modifiable Information (AMI)
The airline can use a ground base software tool (GBST) to re-configure the FDCFs.
Communications Program Interfaces (CPI) I/O
The communications program interfaces of the FDCF supplies a common interface for data communications in the AIMS cabinets. To do this, the CPI supplies a common protocol for the AIMS backplane bus for data transfer. This supports the FDCF intracabinet data exchanges.
The CPI I/O of the FDCF supplies a common interface for data communications to the other AIMS cabinet. The primary and secondary FDCFs exchange data for redundancy management. To do this, the CPI supplies a common protocol for the intercabinet buses 1 and 2.
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DCMS -FDCF FUNCTIONAL DESCRIPTION
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DCMS -DCMF AND FDCF AIRLINE MODIFIABLE INFORMATION
General
The data communication management system (DCMS) has a data communication management function (DCMF) and a flight deck communication function (FDCF). Together the two make up the functionality of ACARS. The design of the 777 airplane lets the airlines customize certain functions in the DCMS. You customize these functions through airline modifiable information (AMI). You use the ground based software tool (GBST) to make the modifications.
The DCMF comes with a default values AMI. The default values AMI has values that determine these:
*
VHF data frequencies
*
ACARS reject message formats
*
Uplink message routing.
The FDCF comes with a baseline AMI. The baseline AMI defines these:
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Baseline flight deck communication display formats
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Basic screen reports
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Downlink messages and formats
*
Uplink messages and formats
*
Logic units and parameter definitions.
DCMF VHF Data Frequency Selection Tables
The default VHF data frequency selection table includes this information:
EFFECTIVITY
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Frequencies
*
Scan times
*
A prekey length
*
An enable/disable trigger.
These are the default frequencies:
*
131.550 (ARINC and Australia)
*
131.725 (SITA)
*
131.475 (Canada)
*
131.450 (Japan).
You can enter up to 15 total frequencies in the table. The valid frequency range is 118.000 to 136.975 megahertz.
The default scan time for all frequencies is 126 seconds. You can change the scan time to any rate between 10 and 600 seconds.
The default prekey length is 75 milliseconds. The valid prekey lengths are 53 to 190 milliseconds in increments of one millisecond.
The default setting for the trigger is enable. You can set this to disable.
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DCMS -DCMF AND FDCF AIRLINE MODIFIABLE INFORMATION
ACARS Reject Message
The ACARS reject message format has 69 characters and an HX label that identifies the reject message. Characters 1-10 contain a standard header. Character 11 has the slash character. Characters 12-18 contain the ATA/IATA address. Character 19 has a period. You can not modify these characters.
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