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Handling Errors and Alarms Section 4-8
The ERH and RUN indicators will be lit if an error occurs in the I/O bus caus-
ing a WDT (watchdog timer) error in the CPU Unit, resulting in incorrect I/O
refresh with the Analog Output Unit.
Turn ON the power supply again or restart the system.
For further details, refer to CS-series CS1G/H-CPU@@-E Programmable
Controllers Operation Manual (W339).
Note No error will be detected by the CPU Unit or displayed on the Programming
Console, because the CPU Unit is continuing operation.
ERH Indicator: Lit, RUN Indicator: Not Lit
The unit number for the Analog Output Unit has not been set correctly.
4-8-4 Restarting Special I/O Units
There are two ways to restart Special I/O Unit operation after having changed
DM contents or having cleared the cause of an error. The first way is to turn
the power to the PLC OFF and ON, and the second way is to turn ON the
Special I/O Unit Restart Bit.
Special I/O Unit Restart Bits
The output becomes 0 V or 0 mA during restart.
If the error is not cleared even after turning the Special I/O Unit Restart Bit ON
and then OFF again, then replace the Unit.
Error Error contents Output condition
I/O bus error Error has occurred during data
exchange with the CPU Unit.
Depends on the output hold func-
tion.
CPU Unit monitoring error (See
note.)
No response from CPU Unit dur-
ing fixed period.
Maintains the condition just
before the error.
CPU Unit WDT error Error has been generated in
CPU Unit.
Depends on the output hold func-
tion.
RUN
ERC
ERH
: Lit
: Not lit
Error Error contents Output condition
Duplicate Unit Number The same unit number has been
assigned to more than one Unit
or the unit number was set to a
value other than 00 to 95.
The output value will be 0 V.
Special I/O Unit Setting Error The Special I/O Units registered
in the I/O table are different from
the ones actually mounted.
Bits Functions
A50200 Unit #0 Restart Bit Turning the Restart Bit for any
Unit ON and then OFF again
restarts that Unit.
A50201 Unit #1 Restart Bit
~~
A50215 Unit #15 Restart Bit
A50300 Unit #16 Restart Bit
~~
A50715 Unit #95 Restart Bit
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