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Diagnostics and Troubleshooting
Fault Detection and Troubleclearing
86 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
COMM A
GOOD
−− −
none
COMM A
BOARD
FAILURE
POWER
LED flashes
13 times.
The COMM A port
hardware has a
serious failure.
Executes normally. Replace Comm
board.
COMM A
BOARD NOT
FOUND
POWER
LED flashes
13 times
The main CPU
board has a non-
default address
and no COMM
port installed.
Executes normally.
Install CPU with
optional RS 485
communications
(if not installed)
or set COMM A
station address to
255.
COMM B
GOOD
−− −
none
COMM B
BOARD
FAILURE
POWER
LED flashes
13 times.
The COMM B port
hardware has a
serious failure.
Executes normally.
All Modbus read
block outputs are
frozen at their last
read values.
Replace CPU.
COMM B
BOARD NOT
FOUND
POWER
LED flashes
13 times
The control file
configuration
requires a master
port and no Comm
Port is installed.
Executes normally.
All Modbus read
block outputs are
frozen at their last
read values.
Install Comm
Board or
download a
configuration that
has no Modbus
slave blocks
PANEL
(OI)
NORMAL
−− −
none