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Siemens AG
Entry type: FAQ Entry ID: 14637869, Entry date: 01/30/2014

Why is there no yellow-and-red emergency stop button on the tethered-connection mobile panel?

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Hand-held controllers with yellow-and-red emergency stop button must not be replugged during operation. When not in operation, they must be stored so that they are inaccessible to untrained personnel who might mistake them for emergency-stop command devices. For the sake of operational safety it is important that emergency-stop command devices are always ready for operation and that there can be no mix-up with emergency-stop command devices that are not ready for operation.

The SIMATIC Mobile Panels 170, 177 and 277 (tethered connection) have a gray STOP button for safe machine stop in compliance with EN60204-1. Since the STOP button is not marked like an emergency-stop switch and has a different color, there is no risk of mistaking it for an emergency-stop switch. For this reason, it is allowed to replug a SIMATIC Mobile Panel during operation despite emergency-stop function and it may also be stored openly when not in operation. The STOP button can be looped into the emergency stop circuit through the connection box in which case it has the same function as an emergency stop switch.

Fig. 1: STOP button of Mobile Panel 170

There must also be emergency stop devices (yellow and red) that are permanently installed to ensure that the plant can be stopped in an emergency by anyone.

The Mobile Panel 277F IWLAN has a yellow-and-red emergency stop button.