diffrence between MODBUS master and MODBUS slave

Hi,

What is the defference between modbus master and modbus slave?

and does it matter to specify this when i am using an OPC server?

thanks for replies.

A Modbus conversation is between two devices at a time, the master and the slave. The master is the only device that can initiate a transaction. It sends commands to read data from or write data to the slave. The slave can only respond to commands from the master. The Modbus protocol does not provide for a peer-to-peer mode.

It may be possible that you can purchase an OPC server that can be configured as either a master or a slave, but you are correct to be asking the question.