Open aigefjk opened 2 years ago
For historical reasons, user reference numbers were expressed as decimal numbers with a starting offset of 1. However MODBUS uses the more natural software interpretation of an unsigned integer index starting at zero.
So a MODBUS message requesting the read of a register at offset 0 would return the value known to the application programmer as found in register 4:00001 (memory type 4 = output register, reference 00001).
For historical reasons, user reference numbers were expressed as decimal numbers with a starting offset of 1. However MODBUS uses the more natural software interpretation of an unsigned integer index starting at zero.
So a MODBUS message requesting the read of a register at offset 0 would return the value known to the application programmer as found in register 4:00001 (memory type 4 = output register, reference 00001).
Modbus client myClient.WriteSingleRegister(0, Value) update value in register 4:00001, but in modbus server localArray[1] presents 4:00001 , that not keep the same style.
I can confirm this.
I can read and write using the same address on the server side. I can also due the same on the client side.
However, using another client, shows, that the data gets writen to different locations. (Client is +1)
When I test V5.5 library,I found there are differences between Modbus server register index and Modbus client register index.
Index of registers Modbus client class used is from 0 , while index of registers Modbus server class used is from 1.
e.g:
If you want to get value in holding register 0, you need pass index 0 to modbus client method but in modbus server method you must pass index 1 to the method.
public void WriteSingleRegister(int Addr, short Value) { MyServer.holdingRegisters.localArray[Addr + 1] = Value; }