Multi-Master support in ModbusTCP network.
In one of our project we are trying to have concurrent TCP connection to Modbus TCP slave. Can anyone help me out with the same or advice whether the same is possible.
The modbus TCP slave will be connected to both CI867 and Energy management system simultaneously as modbus TCP master.
Thank you in advance.
The number of parallel TCP client connections a modbus TCP Server can provide varies from device to device.
A simple way to find out if the Modbus TCP server can simultaneously serve two clients is by reading registers from the server via two instances of Modscan32 in TCP mode. The two instances may run on the same laptop or may run on different laptops.
Connect to the server via the 1st instance and check whether data can be read. Next, connect to the server via the 2nd instance and check whether data can be simultaneously read by both Modscan32 instances.
In AC500 PLC, when the PLC is configured as a server, the number of parallel clients it can serve is determined by the parameter 'Server Connections'. If the parameter is set to 2 (Max 12), then two clients can simultaneously connect to the PLC acting as a TCP server.
In this example, a 3rd instance of Modscan32 will not be able to connect to the PLC (Unless you play around with the TCP connection and disconnection settings and query frequency).