A Redundant Comport consists of primary and backup communications Ports on the SCADA node. This enables a redundant communications path to the automation Device (e.g. PLC or Controller). If communications cannot be established through this Comport, WebAccess will try a second Comport, specified as the Backup Port. You configure the backup Port number in WebAccess, but without any devices on it. Usually the device must have two comports also. Not all Device Types support a backup Port.
The Backup Port is usually configured as the same type. However, some Device Types allow the backup port to be another physical type; for example, Modicon Device can use a TCP/IP (network) port as a backup port to a Serial Port.