The Computer
5-12 Manual # 42-02-1P21
Troubleshooting Specific Problems
This section will describe how to solve some specific problems by using the computer panel.
Problem: BOTTOM FLOOR OR TOP FLOOR DEMAND message. The BOT-
TOM FLOOR OR TOP FLOOR DEMAND message is scrolling on the top line of the LCD dis-
play. The Status and Error Messages list (page 6-4), indicates that the message means that there
is either a Bottom Floor Demand or a Top Floor Demand. The controller is trying to establish
the position of the car by sending it to either the bottom or top floor.
If the controller has the Absolute Floor Encoding feature, then the controller can establish the
position of the car as soon as the car reaches any door zone. The car does not have to travel to a
terminal landing to establish the position of the car.
It is normal for the BOTTOM FLOOR OR TOP FLOOR DEMAND message to appear on the dis-
play right after power up, after the car is taken off Inspection, or after the RST B computer reset
button is pressed. However, in all of these cases, the message should be cleared quickly and
then it should not be seen again as the car runs on Normal service.
If the BOTTOM FLOOR OR TOP FLOOR DEMAND message is scrolling for no apparent rea-
son, take the following steps:
The first step in troubleshooting is to decide which of the following scenarios applies:
Scenario A: The car is stuck at the bottom floor with the BOTTOM FLOOR OR TOP FLOOR
DEMAND error message scrolling constantly.
Scenario B: The car runs normally until it reaches the top floor, then the BOTTOM FLOOR
OR TOP FLOOR DEMAND error message scrolls and the car goes to the bottom floor. When it
reaches the bottom, the message is cleared and the car functions normally until it again reaches
the top floor.
Scenario C: The car runs normally until it reaches the bottom floor. Then the BOTTOM
FLOOR OR TOP FLOOR DEMAND error message scrolls and the car goes to the top. After it
gets there, the message is cleared and the car runs normally until it again reaches the bottom
floor.
What to do for Scenario A: A Bottom Floor Demand should be cleared when all of
the following conditions are met:
1. The car is at the bottom and the Down Slow Down (DSD) input to the controller is OFF.
2. The Door Zone (DZ) input to the controller is ON.
3. The Door Lock (DLK) input to the controller is ON.
4. The leveling signals ULM(LU), DLM(LD) are OFF.
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