I need your technical guidance please, we are looking for a solution to integrate a Public Address System that can communicate over Ethernet TCP/IP with a BMS system that supports MODBUS.
How to let this PA system talk to BMS over MODBUS?
You will probably need a Modbus gateway of some sort, but your question is far too general for anyone to help you further.
The term "Ethernet TCP/IP" provides little more information about your Public Address System than simply saying it has an Ethernet port. We need to know what Ethernet protocol the PA system uses. For example, Modbus/TCP is by definition an Ethernet TCP/IP protocol.
If possible, it would be helpful if you can provide links to any documentation, user's manuals, or communication manuals for the PA system.
Also, please specify whether your BMS system requires Modbus RTU (RS-485) or Modbus/TCP (Ethernet).