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9 Troubleshooting and Maintenance
9-52
CJ-series Serial Communications Units Operation Manual for NJ-series CPU Unit(W494)
Event name Transmission Error (CRC Error) Event code 846D 0000 hex
Meaning A CRC error occurred.
Source PLC Function Module Source details CJ-series Unit Detection
timing After serial com-
munications start
Error attributes Level Observation Recovery --- Log category System
Effects User program Continues. Operation Not affected.
System-defined
variables Variable Data type Name
None --- ---
Cause and
correction Assumed cause Correction Prevention
Noise Implement noise countermeasures. Use the Unit away from sources of
noise. Implement noise countermea-
sures.
CRC calculation method does not
match the device. Correct the CRC calculation method
in the user application to match the
Modbus specifications. Set the CRC calculation method in
the user application to match the
Modbus specifications.
Attached
information Attached information 1: Port number where error was detected
Precautions/
Remarks You can check the number of transmission errors (i.e., CRC errors) in the *_P1_MbsCRCErrCnt and
*_P2_MbsCRCErrCnt device variables.