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164 UDC2500 Universal Digital Controller Product Manual 4/07
7.6 Controller Failure Symptoms
Introduction
In addition to the error message prompts, there are failure symptoms that can be
identified by noting how the controller displays and indicators are reacting.
Symptoms
Compare your symptoms with those shown in Table 7-4.
Table 7-4 Controller Failure Symptoms
Upper
Display
Lower
Display
Indicators Controller
Output
Probable
Cause
Trouble-
shooting
Procedure
Upper
Display
Lower
Display
Indicators Controller
Output
Probable
Cause
Trouble-
shooting
Procedure
Blank Blank Off None Power Failure 1
OK OK Current
Proportional Output
2
OK OK Three Position
Step Control
Output
3
OK OK Time Proportional
Output
4
OK
Displayed
Output
disagrees
with Controller
Output
OK
Controller
Output
disagrees
with Displayed
Output
Current/Time
Proportional Output
5
OK OK OK External Alarm
function does
not operate
properly
Malfunction in
alarm output
6
Display does not change when a key is pressed Keyboard
Malfunction
7
Controller fails to go into “Slave” operation during communications Communications
Failure
8
OK Displayed
Output
disagrees with
Auxiliary Output
OK
Controller
Auxiliary Output
disagrees
with Displayed
Auxiliary Output
Auxiliary Output 9
Other symptoms
If a set of symptoms or prompts other than the one you started with appears while
troubleshooting, re-evaluate the symptoms. This may lead to a different troubleshooting
procedure.