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3) When the computer select switch is set to AUTO position, the relays in the switching modules are set to the left computer inputs. If the left computer fails, it will ground its LCU fail discrete, which in turn causes the relays to switch to the right computer inputs.
(e) Display Units
1) Each display unit receives intensity control signals from its own local light sensor, the other display unit light sensor, the left EFIS remote light sensor, and from the display select panel. These signals, along with a day/night discrete from the master dim and test system, provide information to the brightness control microprocessor.
2) Digital line receivers take red, green, and blue analog signals and send them on through color desaturation logic to the beam monitor. The monitor then uses the X and Y deflection signals, sync and strobe/intensity signals, and the bright intensity microprocessor outputs to drive the display crt.
(11) Display Pages (Fig. 13)
(a)
The display page logic uses inputs to the computer to assemble display pages. Analog and digital inputs provide direct input to the logic for parameter indicators, as well as providing information for automatic exceedance display state changes. If an exceedance occurs, this information is also used to take an auto event snapshot, if necessary. Alert, status, and maintenance message page logic provides inputs to include messages on the display pages.
(b)
Manual and Auto Event data for ECS/MSG, ELEC/HYD, and PERF/APU pages is stored in non-volatile memory (NVM). When the display page logic chooses maintenance data for display, it selects Manual Event, Auto Event, or real-time for display.
(c)
Display requests for the display select panel control which format is to be displayed. When an event occurs to cause a display change, the display state logic looks at the present display conditions on the top and bottom display units to decide what new formats should be displayed. Display commands are then set to the display controller.
B. BITE (Fig. 14)
(1) EICAS incorporates extensive BITE monitoring. This monitoring isolates system failures to LRU's, if possible. It provides detected faults using EICAS messages. A self-test mode can also be initiated manually.
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