777 AIRCRAFT MAINTENANCE MANUAL
CMCS -FIBER OPTICS INTERFACE
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CMCS -ARINC 429 DATA LOAD INTERFACE
General
The central maintenance computing function (CMCF) in the AIMS cabinets supplies data load display formats that appear on the MAT display unit. The data load display formats let the maintenance crew select the source of the data and the destination of the data.
The source of the data is a data file on the hard drive or on a disk in the disk drive. The destination is one of these:
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An ARINC 429 LRU
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An LRU on a systems ARINC 629 bus
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An LRU on a flight controls ARINC 629 bus
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An LRM in the AIMS cabinet.
When the crew selects the source and the destination, the MAT sends the data through the fiber optics interface to the CPM/ COMM in the AIMS cabinets. The CMCF sends the data to the correct LRU or LRM on a designated data load port through an IOM.
ARINC 429
The data goes out on the ARINC 429 data load bus.
Along with the data, load enable discretes go to the ARINC 429 LRUs.
Data and status information comes in from the ARINC 429 LRUs on the 429 data input buses.
Training Information Point
These are the times when you must change the active CMCF to do a data load:
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To load some LRUs on the flight controls ARINC 629 buses
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To load a 429 LRU connected to the right AIMS cabinet when the left CMCF is active.
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To load a 429 LRU connected to the left AIMS cabinet when the right CMCF is active.
Use the central maintenance computer switch control from the other functions menu to switch the active CMCF.
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777 AIRCRAFT MAINTENANCE MANUAL
CMCS -ARINC 429 DATA LOAD INTERFACE
EFFECTIVITY BEJ ALL 45-10-00
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CMCS -FLIGHT CONTROLS ARINC 629 BUS DATA LOAD INTERFACE
Flight Controls ARINC 629 Data Buses
The data load information goes to the flight controls system LRUs on the left, center, or right flight controls ARINC 629 data buses.
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CMCS -FLIGHT CONTROLS ARINC 629 BUS DATA LOAD INTERFACE
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CMCS -SYSTEMS ARINC 629 BUS DATA LOAD INTERFACE
Systems ARINC 629 Buses
The data goes to the airplane system LRUs on the left, center 1, or right systems ARINC 629 data bus. No data goes out on the center 2 systems ARINC 629 data bus.
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CMCS -SYSTEMS ARINC 629 BUS DATA LOAD INTERFACE
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CMCS -ARINC 429 INTERFACES
CMCS ARINC 429 Bus Control
The central maintenance computing system (CMCS) buses connect the left and right AIMS cabinets with LRUs that use the ARINC 429 standard for digital data transfer. The CMCF supplies data to three low speed ARINC 429 transmitters in each AIMS cabinet. Three source select relays in the left AIMS cabinet select between the left and right AIMS cabinets as the data source to the LRUs.
The left CMCF controls the source select relays. If the left CMCF is the primary CMCF, the relays are energized and the left CMCF supplies the outputs on the CMCS buses.
If an IOM fails in the left AIMS cabinet, the relay relaxes in that IOM and the data comes from the right CMCF.
If the left CMCF fails, all three relays relax and the data on the CMCS buses comes from the right CMCF.
CMCS ARINC 429 Outputs
The LRUs that receive data on the CMCS buses are the:
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ATC mode S transponder; left and right
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ADF receiver; left and right
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Cabin telecommunications unit (CTU)
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DME interrogator; left and right
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Flight compartment printer
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GPWC
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HF communication transceiver; left and right
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Multi-mode receivers (MMRs); left, right and center
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Radio altimeter receiver/transmitter; left, right and center
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Satellite data unit
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TCAS computer
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VHF communication transceiver; left, right and center
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