Honeywell UMC800 User Manual
Page 90

Diagnostics and Troubleshooting
Fault Detection and Troubleclearing
82
UMC800 Controller Installation and User Guide
Release F
4/01
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
SYSTEM
TASK FAULT
RUN LED
off.
And
POWER
LED flashes
3 times.
Software failure.
Function blocks are
not executed.
1.
Force a cold
start. (Toggle
controller mode
switch from
PGM to RUN.)
2.
Upgrade
controller
software.
3.
Replace CPU
board.
4.
Contact
Honeywell.
CPU
GOOD
−
−
−
none
CPU
WATCHDOG
POWER
LED flashes
3 times.
Watchdog reset
resulting from
software failure.
Executes normally.
1.
Force a cold
start. (Toggle
controller mode
switch from
PGM to RUN.)
2.
Upgrade
controller
software.
3.
Replace CPU
board.
4.
Contact
Honeywell.
CPU
BUS ERROR
POWER
LED flashes
4 times.
Bus Error
Detected.
Executes normally.
1.
Force a cold
start. (Toggle
controller mode
switch from
PGM to RUN.)
2.
Isolate system
from noise and
force a cold
start.
3.
Replace CPU
board.