Mitsubishi Electric Melsec QJ71LP21 Reference Manual page 422

8 TROUBLESHOOTING
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(3) Checking for data link error
When a data link is not available, check the following link special registers.
1) SW0048: Cause of the baton pass interruption
2) SW0049: Cause of the data link stop
3) SW0055: Parameter setting status
(4) Checking for dedicated instruction error
Error codes for the errors occurred during execution of a dedicated instruction
can be checked by the following device data.
Error codes for transient transmission errors are stored in the link special
registers SW00EE to SW00FF as well.
For details of each instruction, refer to programming examples for dedicated
instructions described in Section 7.4.5
1) SEND, RECV, RECVS, READ, WRITE, REQ:
Completion station (S1) + 1 of the control data
2) ZNRD : SW31
3) ZNWR : SW33
4) RRUN, RSTOP, RTMRD, RTMWR : SW0031 (When channel 1 is used.)
MELSEC-Q
SW0033 (When channel 2 is used.)
SW0035 (When channel 3 is used.)
SW0037 (When channel 4 is used.)
SW0039 (When channel 5 is used.)
SW003B (When channel 6 is used.)
SW003D (When channel 7 is used.)
SW003F (When channel 8 is used.)
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