Mitsubishi Electric NZ2FTGN User Manual page 292

If F0 (error occurrence flag) is turned on, check the following.
Item
A value other than the normal value (0000H) is stored in D101.
A value other than the normal value (0000H) is stored in D102.
11 NZ2FT-MT
290
11.4 Functions
Action
Refer to the following and take action.
 MODBUS/TCP Interface Module User's Manual (Details)
Refer to the following and take action.
Page 321 MODBUS abnormal response code