AC900F Modbus TCP port maximum slaves
Voted best answer
There is no limit per port. You can configure 20 Modbus TCP connections per AC 900F controller, distributed between avaliable ports as You see fit. The limit is really put on number of Ethernet interface objects, so interfaces like: Modbus TCP Master/Slave, Telecontrol (60870-5-104) Master/Slave, Send/Recive etc. The standard communication (ControlNet, Redundacny Link) does not count into this limit. You can use all 20 for Modbus TCP Master (but then You have nothing for those other functions).
Hope this helps,