Configuring Redundancy

The S7TCP driver supports multiple I/O server / device redundancy. The driver represents each S7-PLC as a separate I/O device. In normal operating state, the driver will poll the PLC via the primary I/O device. If the connection to the PLC via the primary I/O device is lost, the PLC will be polled via a standby I/O device which is connected to the PLC and has the highest priority in case when multiple redundant I/O devices are configured.

Note: The redundancy switchover will only work properly if Plant SCADA periodically checks the communication connection to the primary and standby I/O devices. Plant SCADA automatically checks the primary I/O device, but this process can be disabled for the standby I/O device if the I/O server parameter [IOServer]WatchDog is set to 0 (disabled). By default, this parameter enables Watch Dog functionality for a standby I/O device. It should not be changed.