User`s manual

104
FX3U Series Programmable Controllers
User’s Manual - MODBUS Serial Communication Edition
12 Troubleshooting
12.5 Checking Setting Contents and Errors
2. Communication setting using parameters
Verify that the communication setting parameters are suitable for use. If the communication setting
parameters are not suitable for use, communication will not function correctly. After changing any setting,
make sure to reboot the PLC's power.
→ For the MODBUS communication settings, refer to Chapter 5.
3. Presence of RS or RS2 instructions
Verify that neither the RS nor RS2 instructions are being used on the same channel as the MODBUS
communication.
If either instruction is being used on the same channel, delete it, and then reboot the PLC's power.
4. Presence of IVCK, IVDR, IVRD, IVWR, and IVBWR instructions
Verify that none of the dedicated Inverter communication instructions are being used on the same channel as
the MODBUS communication.
If any of the instructions are being used on the same channel, delete it, and then reboot the PLC's power.
12.5 Checking Setting Contents and Errors
1. Checking the setting contents
Each FX PLC has devices for checking the communication settings. Verify that the correct contents are
stored in the devices shown in the table below.
Device Name Description
D8400
Channel 1 MODBUS
Communication Format
For Descriptions, refer to Chapter 6.
D8401
Channel 1 MODBUS
Protocol
D8409
Channel 1 MODBUS
Slave ResponseTimeout
D8410
Channel 1 MODBUS
Turn Around Delay
D8411
Channel 1 MODBUS
Message to Message Delay
D8412
Channel 1 MODBUS
Number of Retries
D8414
Channel 1 MODBUS
Slave Node Address
D8415
Channel 1 MODBUS
Communication Status
Information Setup
D8416
Channel 1 MODBUS
Communication Status
Device Range Setup