Mitsubishi Electric MELSEC Q Series Reference Manual page 296

8 TROUBLESHOOTING
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(b) For the remote I/O module
POINT
If the status of the "T. PASS" LED is unstable, refer to the following.
<Cause>
The line status may be unstable.
<Troubleshooting>
1) Check the connector for loose connection and the cable for a break.
2) Check that the cable used conforms to the specifications.
3) Check that the overall length and interstation distance conform to the
specifications. (Refer to Section 4.8 Cable Connection.)
MELSEC-Q
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