Appendix; Appendix 1 Troubleshooting; Modbus Serial Communication; Modbus/Tcp Communication - Mitsubishi Electric MELSEC iQ-F FX5 User Manual

APPENDIX

Appendix 1

MODBUS serial communication

When an error occurs with MODBUS serial communication, check the following items.
Checking the communication status based on LED indication
Check the status of the "RD" and "SD" indicator LEDs provided.
LED status
RD SD
Lit Lit
Lit Unlit
Unlit Lit
Unlit Unlit
While MODBUS serial communication is functioning normally, both LEDs are lit.
If they are not lit, check the wiring, communication settings, and error statuses of the master and slave stations.
Checking the installation and wiring
■Mounting status
Verify that the communication equipment is securely connected with the CPU module, the expansion board or the expansion
adapter. If the communication equipment is not securely connected, communication will not function correctly.
For the mounting procedure, refer to the respective communication equipment manual.
■Wiring
Verify that all communication equipment is correctly wired. If the wiring is incorrect, communication will not function correctly.
For the wiring check method, refer to Page 22 WIRING.
Checking parameters
■Communication setting of parameters
Verify that the communication setting parameters are suitable for use. If the communication settings are not suitable for use,
communication will not function correctly. After changing any parameters, make sure to turn off the CPU module power, and
then the power on again, or reset.
For the MODBUS communication settings, refer to Page 27 COMMUNICATION SETTING.

MODBUS/TCP communication

When an abnormality occurs in MODBUS/TCP communication, confirm the detail of abnormality with Ethernet diagnostics.
(MELSEC iQ-F FX5 User's Manual (Ethernet Communication))
Troubleshooting
Operation status
Data is being sent and received.
Data is received, but is not sent.
Data is sent, but is not received.
Data is neither sent nor received.
APPX

Appendix 1 Troubleshooting

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