Siemens S7-1200 - MB_SERVER Example: Multiple TCP Connections

Communication processor and Modbus TCP
12.5 Modbus communication
S7-1200 Programmable controller
742 System Manual, 03/2014, A5E02486680-AG
12.5.2.3
MB_SERVER example: Multiple TCP connections
You can have multiple Modbus TCP server connections. To accomplish this, MB_SERVER
must be independently executed for each connection. Each connection must use an
independent instance DB, connection ID, and IP port. The S7-1200 allows only one
connection per IP port.
For best performance, MB_SERVER should be executed every program cycle, for each
connection.
Network 1:
Connection #1 with independent IP_PORT, connection ID, and instance DB
Network 2:
Connection #2 with independent IP_PORT, connection ID, and instance DB