@@plc_Electrical Sir, have any solution about modbus? I have completed modbus with Delta 28SV2 PLC to MS300 VFD Rs-485 and PLC to DOPB07S411 HMI Rs-232 communication. But PLC only Rs-232 led blinking, Rs-485 led not blinking. But from pc, all process are working. At this moment how can I do? Have any help or suggestion?