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Error Processing Section 7-7
7-7-1 Fatal Errors (ERR Indicator Lit)
Note DM allocation errors are indicated in the Simple Communications Unit status
word. (Refer to Simple Communications Unit Status on page 239 for details.)
7-7-2 Non-fatal Errors (ERR Indicator Flashing)
Note 1. Details on communications errors can be found in the Response Monitor
Area. See Response Monitor Area on page 246 for details on errors that
occur while reading or page 248 for details on errors that occur while writ-
ing.
2. Syntax errors are indicated in the Simple Communications Unit status
word. (Refer to Simple Communications Unit Status on page 239 for de-
tails.)
Error Likely cause and correction
Communications cannot be estab-
lished with the CPU Unit.
Check the communications baud rate and other communications settings
in the CPU Unit and Simple Communications Unit. Correct the settings
and turn ON the Simple Communications Unit again.
There was a communications error
with the CPU Unit.
Noise can cause communications errors. If noise is suspected, use cables
and wiring methods that will reduce noise in the communications lines and
turn ON the Simple Communications Unit again.
Cannot write data while the CPU
Unit is in RUN mode.
Check whether the CPU Unit is in RUN mode. If so, switch the CPU Unit to
MONITOR mode or PROGRAM mode and turn ON the power again.
A watchdog timer error occurred. Watchdog timer errors are indicated in the Simple Communications Unit
status word. (Refer to Simple Communications Unit Status on page 239.)
It is possible for noise to affect the Simple Communications Unit’s pro-
cessing. If noise is suspected, take steps to reduce noise around the Unit
or shield the Unit.
The watchdog timer error can be cleared by turning the power supply OFF
and then ON again.
DM allocation error (See note.) The DM allocation may exceed the boundary of the CPM2C’s DM Area.
When a DM allocation error is detected, error code “15” is written to the
Simple Communications Unit Status word (see page 239).
To restore normal operation, correct the DM allocation and switch the Unit
from RUN to Stop and then back to RUN again. Refer to Simple Communi-
cations Unit Control on page 238 for details on the RUN/Stop Digit.
Error Likely cause and correction
There was a communications error
with a component. (See note 1.)
Check whether the communications settings in the components match the
settings in the Simple Communications Unit. Correct the settings if neces-
sary. Normal operation will be restored when the cause of the communica-
tions error is corrected.
Noise can cause communications errors. If noise is suspected, use cables
and wiring methods that will reduce noise in the communications lines.
Normal operation will be restored when the cause of the communications
error is corrected.
Syntax error (See note 2.) A syntax error occurs when there is an error in the DM settings.
When a syntax error is detected, error code “02” is written to the Simple
Communications Unit Status word (see page 239) and the DM word
address is written to the Syntax Error DM Address word (see page 239).
To restore normal operation, correct the setting in the indicated DM word
and switch the Unit from RUN to Stop and then back to RUN again. Refer
to Simple Communications Unit Control on page 238 for details on the
RUN/Stop Digit.