More PLCs can be connected over a serial line. This is useful at sites where only serial cabling is available, such as at refurbishments. In the PLC which acts as a TCP to serial router, in the PLC setting a unique SSCP address (link address) must be set, "Enable Serial Router", "Serial Router Port", and "Serial Router Baudrate".
The serial port must not be used for any other purpose, such as communication to I/O modules.
Upload the configuration to PLC, right click the PLC -> PLC Operation -> PLC Setup -> Upload configuration to PLC. Upload the configuration over UDP broadcast, and restart the PLC.
In the PLCset over the TCP connection a unique "SSCP Address" (link address), "Enable Serial Server", "Serial Server Port" and "Serial Port Baudrate". Each PLC on the serial line must have an unique SSCP link address..
The serial port must not be used for any other purpose, such as communication to I/O modules.
Upload the configuration to PLC, right click the PLC -> PLC Operation -> PLC Setup -> Upload configuration to PLC. Upload the configuration over UDP broadcast, and restart the PLC.
In the parameters for connection to PLC, keep the TCP connection type, and set the router IP address, and SSCP address which was set up in the serial servers. If the incoming packets are damaged or bad, make sure the RS485 line is terminated properly.
Topology for more PLCs as serial servers:
Example of configuration for the above topology.
Parameter | PLC1 - serial router | PLC2 - serial server | PLC3 - serial server |
---|---|---|---|
Connection parameters | |||
Server | 192.168.1.11 | 192.168.1.11 | 192.168.1.11 |
Network settings | |||
IP address | 192.168.1.11 | 192.168.1.12 | 192.168.1.13 |
SSCP parameters | |||
SSCP address | 1 | 2 | 3 |
Serial server enable | False | True | True |
Serial server port | not important | COM3 (485) | COM1 (485) |
Serial server baudrate | not important | 11520 | 11520 |
Serial router enable | True | False | False |
Serial router port | COM1 (485) | not important | not important |
Serial router baudrate | 115200 | not important | not important |