The new PROTECT-IE input extension module from Schmersal enables up to four (2-channel) emergency-stop control devices, safety interlock switches and/or other protective devices with floating contacts to be connected to each module, with the ability to cascade up to twenty modules (eighty sensors) in series. Two versions are available depending on the configuration of the sensor channels. The PROTECT-IE-02 is used for all 2-channel emergency-stop control devices, safety switches (including safety solenoid switches) and/or protective devices with floating NC contacts. Devices with NC/NO combinations are wired to the PROTECT-IE-11. Both modules use LED’s to indicate the respective switched status. When a signal changes, for example if a guard is opened or closed, the PROTECT-IE generates an additional diagnostic signal per sensor that can be processed by a control system for visual and diagnosis purposes. This additional signal rules out incorrect information being passed to the fault management unit of a machine control. Significant savings can be made in the time taken to wire safety circuits, as there is no need for additional wiring of signalling contacts to determine which series-switched emergency-stop control devices have been actuated, or which guard has not been closed. Installations normally achieve control category 3 to EN 954-1, but control category 4 can be achieved if certain errors can be ruled out by additional measures.