(c)
The EICAS Display Select Panel receives input discretes from the maintenance panel and the CANCEL and RECALL switches. These discretes, along with discretes from controls on the display select panel, are used by the data management controller to formulate display requests. These requests are sent in identical digital data words to both EICAS computers over separate ARINC 429 buses.
(d)
A computer select discrete is sent from the display select panel to relays in the EICAS switching modules. If this line is an open circuit, the left computer will drive the displays. If this line is grounded, the right computer will drive the displays.
(e)
An LCU fail discrete is used to accomplish automatic switching to the right computer if the left computer fails. This grounding discrete is sent from the left computer to the display select panel. If the computer select switch is sent to AUTO, the computer select discrete line is grounded, switching the display units and modules over to the right computer.
(7) Digital Inputs (Fig. 8)
(a) Each EICAS computer receives digital inputs in both high and low speed ARINC 429 formats.
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DIGITAL INPUTS
RIGHT EICAS COMPUTER
EICAS Digital Inputs Schematic
Figure 8
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(b) These sources send low speed data to the EICAS computers
listed: ~.................................................................. | SOURCE______ | EICAS COMPUTER (S)
__________________| .................................................................... | Air data computer, left | L | .................................................................... | Air data computer, right | R | .................................................................... | Airborne vibration monitor, left | L,R | .................................................................... | Airborne vibration monitor, right | L,R | .................................................................... | Electronic Engine Control, left | L,R | .................................................................... | Electronic Engine Control, right | L,R | .................................................................... | EICAS Display select panel | L,R | .................................................................... | Engine Pressure Ratio (EPR) | L,R | | transmitter, left | | .................................................................... | Engine Pressure Ratio (EPR) | L,R | | transmitter, right | | .................................................................... | Flight management computer (FMC), | L | | left | | .................................................................... | Flight management computer (FMC), | R | | right | | .................................................................... | Fuel quantity processor unit, left | L,R | .................................................................... | Radio altimeter, left | L | .................................................................... | Radio altimeter, right | R | .................................................................... | Thrust management computer | L,R | 2.........................................…........................1
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本文链接地址：757 AMM 飞机维护手册 仪表 CHAPTER 31 - INSTRUMENTS 2(32)
