The 852 series ethernet switches from Wago offer an alarm contact switch to signal an error condition on the switch. This feature is standard on both managed and unmanaged switches (non-ECO versions). The power input connector on the switch has two dedicated alarm circuit connections that can be wired to any warning device, such as a PLC or pilot light. Error conditions that can be monitored include port link failure (cable disconnect, network disruption, etc.), power supply disruption/disconnect, or power supply voltage out of specified range (9 to 48 v). The alarm contact feature, which is enabled via dip switch, is suitable for use in factory and process automation applications. For example, the alarm circuit could be wired to the input of a PLC and be monitored by that PLC, and a procedure could be created in the PLC code to handle the fault condition, resulting in minimized downtime.