A safety device is provided that can be connected with a technical device and an associated emergency activation apparatus. The safety device includes a rail. The rail and emergency activation apparatus are fashioned such that the emergency activation apparatus can be attached to the rail and be shifted thereon. A test signal can be output by the rail that can be received by an emergency activation apparatus attached thereto independent of its shift position. A response signal can be output by the emergency activation apparatus that can be received by the rail independent of the shift position emergency activation apparatus. The safety device is fashioned such that a signal can be emitted to the technical device dependent on the receipt of the response signal. Via the signal, an emergency measure can be triggered, for example an emergency disconnection of the technical device such as an E-stop or, respectively, dead-man's function.