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Diagnostics and Troubleshooting
Fault Detection and Troubleclearing
Release F UMC800 Controller Installation and User Guide 81
4/01
Fault Detection and Troubleclearing
Interpreting the controller status and determining if any corrective action is necessary can be done by
referring to Table 20 and Table 21. Actions to clear fault conditions usually consist of restarting the
controller, and if the fault reoccurs, replacing the suspected faulty component. It is recommended that you
replace controller components only after performing all other actions listed for that fault condition.
NOTE: The controller status POWER LED is used to indicate a number of faults. A diagnostic fault
causes the POWER LED to flash. The LED will flash a number of times to indicate the type of fault
detected. (See the column “Controller LED on CPU” in Table 20.) The LED flashes quickly a number of
times followed by a long off period. This is similar to a telephone answering machine which uses a
flashing LED to indicate the number of messages. This indication is helpful when the operator interface or
PC is not connected or is not communicating with the controller.
ATTENTION
When replacement of a controller component is necessary, refer to procedures in
Maintenance section.
Table 20 Details of the diagnostic summary display
Controller
Diagnostic Summary
(In the User Utility and Operator
Interface)
Controller
LED on CPU
Fault Detection / Troubleclearing
Menu
Item
Status Possible Cause Controller Action User Action
−−
POWER
LED flashes
1 time.
RAM failed on
power-up.
Executes an infinite
loop that toggles
the LED.
Communications
and control are
disabled.
Cycle power;
If fault reappears,
replace CPU.
SYSTEM
GOOD RUN LED on Controller is in
RUN mode.
Executes the run
mode.
None
SYSTEM
OFFLINE MODE RUN LED
flashes.
Controller is in
OFFLINE mode.
Executes the
Offline mode.
None
SYSTEM
PROGRAM
MODE
RUN LED
off.
Controller is in
PROGRAM mode.
Function blocks are
not executed.
None
SYSTEM
INVALID
CONFIG.
RUN LED
off.
And
POWER
LED strobes
12 times.
A configuration
with more than 8
loops was
downloaded to an
8 loop controller.
Incomplete
download of
configuration files.
Empty database
created.
Download
previous valid
configuration.