A reason varies with the connection situation of options. (Please refer to the section 6 of the User’s Manual.)
 

In case of MODBUS RTU
Error content: Communication error such as an address error
Please refer to the User’s Manual for error codes and error contents.
Countermeasure: Check the register addresses, function code and the communication settings.
If the correct query received, [COM] is lit.
 

In case of MODBUS TCP (ME-0000MT-SS96)
Error content: Communication error such as a data error of the TCP header part and an address error
Please refer to Section 6 of the “LSPM0075” for error codes and error contents.
Countermeasure: Check the data of the header part and the communication settings.
If the correct query received, [COM] is lit.
 

In case of CC-Link (ME-0040C-SS96)
Error content: Hardware error
Countermeasure: Check the wiring between the main body of ME96 and the option.
 

In case of Logging unit (ME-0000BU-SS96)
Error content: Setting error, SD memory card error, battery voltage reduction, etc.
Check the LED situation of the option. Please refer to Section 1 of the User’s Manual.
Countermeasure: Refer to Section 1 of the User’s Manual.