D-77
FX Series PLC User's Manual - Data Communication Edition
Computer Link
8 Troubleshooting
8.4 Checking Sequence Program
A
Common Items
B
N:N Network
C
Parallel Link
D
Computer Link
E
Inverter
Communication
F
Non-Protocol
Communication
(RS/RS2 Instruction)
G
Non-Protocol
Communication
(FX
2N
-232IF)
H
Programming
Communication
I
Remote
Maintenance
Apx.
Discontinued
models
8.4 Checking Sequence Program
1. Communication setting in the sequence program
Verify that the parallel link and N:N Network are not set. Verify that the communication format (D8120 and
D8420) is set correctly. Communication is not possible if a communication port is set twice or more.
After changing any setting, make sure to reboot the PLC’s power.
2. Communication setting using parameters
Verify that the communication settings using parameters is suitable to the purpose of use.
If the communication settings are not suitable to the purpose of use, communication will not function correctly.
After changing any setting, make sure to reboot the PLC’s power.
3. Presence of VRRD and VRSC instructions (in FX3U and FX3UC PLCs)
Verify that the VRRD and VRSC instructions are not used in the program.
If these instructions are used, delete them, reboot the PLC’s power.
4. Presence of RS instruction (except FX3U and FX3UC PLCs)
Verify that the RS instruction is not used in the program.
If this instruction is used, delete it, reboot the PLC’s power.
5. Presence of RS and RS2 instructions (in FX3U and FX3UC PLCs)
Verify that the RS and RS2 instructions are not being used for the same channel.
If these instructions are used for the same channel, delete them, reboot the PLC’s power.
6. Presence of EXTR instruction (in FX2N and FX2NC PLCs)
Verify that the EXTR instruction is not used in the program.
If this instruction is used, delete it, then reboot the PLC’s power.
7. Presence of IVCK, IVDR, IVRD, IVWR, and IVBWR instructions (in FX3U and FX3UC PLCs)
Verify that the IVCK, IVDR, IVRD, IVWR and IVBWR instructions are not being used for the same channel.
If these instructions are used for the same channel, delete them, reboot the PLC’s power.