Changing Slave Address by the modbus network

L

Thread Starter

Lélio

Hi, my name is Lelio.

I'm from Brazil. I am starting my studies in the Modbus protocol. I would like to address one question: What code modbus standard used to make the switch addresses of slave devices? For some specific code?

For example: To read data from the slave use the code 3 and so on.

Thanks!
 
> What code modbus standard used to make the switch addresses of slave devices? For some specific code? <

I'm confused to, but

a) slave addresses are not configured through the Modbus protocol. The modbus slave device is designed to have some means of setting a slave node address: DIP switches, keyboard/display, software, whatever. The slave address is saved in some form of non-volatile memory.

b) The Modbus message from the master has a field for the slave's address and a separate field for the command code. The Modbus Standard spells out the format of the message and the reply message from the slave.
 
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