Troubleshooting
8 334183A
Modbus Errors
Modbus errors are typical protocol errors defined by fieldbus specification. The fieldbus error code shown is returned
to the PLC when the error condition occurs.
Code Name Cause Solution
1 Illegal Function Request function is not supported. Use supported Modbus functions:
• Read Holding Register
• Wr ite Holding Register
• Wr ite Multiple Holding Registers
2 Illegal Data Address Exceeded maximum register count
of 121 registers.
Request 121 or fewer registers at a time.
No valid property mapped to the
requested Modbus register.
Verify that the device has valid mapping.
See MBTCP Modbus Error for 4 red
flashes.
Write Holding Register(s) returns
set property error.
Verify that the end device is online.
3 Illegal Data Value
Not implemented.
4 Slave Device Fail Not implemented.
5 Acknowledge Not implemented.
6 Slave Device Busy Not implemented.
8 Memory Parity Error Not implemented.
10 Gatweay Path Unavailable Not implemented.
11 Gateway Target Fail An active system error exists. Refer to system errors table.
255 Unspecified
