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thank you so much sir for resolved my problem.

@AlexUT  any answers on this?  Seems to be surfacing more often. cheers, Aus

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Hi Guys, Could somebody tell me how to add a PLC in Visilogic which is not in the data base?

I think you are confusing the terms:   slave ID is usually used to specify the device on the Modbus Network. in the code that you sent is hardcoded to be 1:  register 400001 and 300001 to me sounds like different function code registers. are you sure that the Masibus Old and New scanner uses different addresses? some background on Modbus: Modbus works using specified registry addresses, and the called function codes: so, 30001 is the first address on the Input registers, and 40001 is the first one on the Holding registers. the difference is that holding registers are Read/Write  and Input registers are only Read. so, if you want to access register 30001 you need to point to addres 0 of Input registers using function code 4 (Read Input registers). the program that you sent is accessing address 0 using function code 3 (Read Holding registers) which happens to be register 40001:   If you are sure that you need to read register 30001 then use the appropriate function code:   Also, some Modbus devices starts counting on 0, others on 1 just to take into consideration.