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AIMS -CABINET CHASSIS POWER DISTRIBUTION FUNCTIONAL DESCRIPTION
Hot Battery Bus
Each LRM also receives one 28v dv power source from the hot battery bus.
The connection to the hot battery bus keeps the LRMs internal memories active. The hot battery bus also makes the AIMS cabinet less likely to have faults due to power transients. The LRMs shut down after 500 msec of hot battery bus power operation.
Training Information Point
The hot battery bus holds the static random access memory (SRAM) with no other power on the airplane. If you remove the battery, you lose some data from the LRMs. The data you lose includes:
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ACMF report data stored on the ACMF CCA
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Fault history data collected by the CMCF.
Power Distribution
Each LRM changes the 28v dc from the backplane power buses into:
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Voltages required by the LRM
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5v dc transceiver voltage
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2v dc termination voltage.
Each LRM sends a 5v dc transceiver voltage to one of the four transceiver power backplanes. This power is used by the transceivers in the LRMs.
Each LRM sends a 2v dc termination voltage to one of the four termination power backplanes. Terminators on the ends of the backplane data buses use the power from the 2v termination power backplanes.
Training Information Point
Each LRM has a hot insertion switch. The switch makes sure that the LRM does not get power until it has positive contact between its connector pins and the backplane pins.
When you install an LRM into the cabinet, this sequence occurs:
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Ground, power, and signal pins in the connector make contact with the backplane ground, power, and signal pins
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Hot insertion switch engages. This lets the power from the backplane go to the power in the LRM.
When you remove an LRM from the cabinet, the reverse sequence occurs.
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AIMS -CABINET CHASSIS POWER DISTRIBUTION FUNCTIONAL DESCRIPTION
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AIMS -CABINET CHASSIS BACKPLANE DATA BUSES FUNCTIONAL DESCRIPTION
General
A signal distribution area goes along the entire width of the rear of the cabinet chassis. This area has four serial backplane data buses. These data buses distribute data between the LRMs.
The data on the backplane buses transfers at a rate of 60 million bits per second (Mbps).
Data Distribution
The serial buses are AX, BX, AY and BY. The buses all transmit the same information. The two serial buses AX and BX come from the X bus interface in the LRM, and are a bus pair. The two serial buses AY and BY come from the Y bus interface in the LRM and are a bus pair. With the dual redundant buses, the LRM can isolate failures in the module.
A serial bus consists of three signal lines. Two of the signal lines are data lines and the third signal line is a clock line. A terminator at each end of a serial bus terminates the three signal lines. The terminator gets power from the termination power backplane bus.
Transceivers in each LRM transmit data to and receive data from the backplane data buses. The LRM transmits data on all four of the serial buses at the same time. The transceivers get power from the transceiver power backplane bus.
The LRM compares the data it transmits on serial buses AX and BX with the data it transmits on serial buses AY and BY.
The duplicate bus pairs supply bit-for-bit identical information. The duplication supplies error detection, isolation, and containment.
Training Information Point
The status message AIMS shows when one or more of the serial backplane data buses fail for one second. All communication can be lost over a serial bus if a transceiver shorts out the serial bus or if power to the terminators fails.
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AIMS -CABINET CHASSIS BACKPLANE DATA BUSES FUNCTIONAL DESCRIPTION
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