Mb_Server Example: Multiple Tcp Connections - Siemens SIMATIC S7 System Manual

See also
TCON, TDISCON, TSEND, AND TRCV (Page 408)
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 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
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
105BCommunication processor
12.5 Modbus communication
595