9. TROUBLESHOOTING
IMS01J02-E4
183
Modbus
Problem Probable
cause
Solution
No response
Wrong connection, no connection or
disconnection of the communication cable
Confirm the connection method or
condition and connect correctly
Breakage, wrong wiring, or imperfect
contact of the communication cable
Confirm the wiring or connector and
repair or replace the wrong one
Mismatch of the setting data of
communication speed and data bit
configuration with those of the host
Confirm the settings and set them
correctly
Wrong address setting
A transmission error (overrun error,
framing error, parity error or CRC-16
error) is found in the query message
Re-transmit after time-out occurs or
verify communication program
The time interval between adjacent data in
the query message is 24-bit time or more
and less than 24-bit time
2 ms *
Set the Modbus mode selection
(COM.PORT3 setting switch, No. 7) to
ON (Modbus mode 2).
The time interval between adjacent data in
the query message is too long,
24-bit time
2 ms or more
Re-transmit after time-out occurs or
verify communication program
Error code 1
Function cod error
(Specifying nonexistent function code)
Confirm the function code
Error code 2
When written to read only (RO) data,
When any address other than 0000H to
1FFFH is specified, etc.
Confirm the address of holding register
Error code 3
When the data written exceeds the setting
range, When the specified number of data
items in the query message exceeds the
maximum number of data items available
Confirm the setting data
* 24-bit time
The time interval between adjacent data
24-bit time
2 ms
For the Modbus mode selection setting, see the
5.1 Protocol Selection and Host
Communication Setting (P. 43).
