Patent ID: 6787940
Filing Date: 2004-09-07
Classification: G05B

Abstract:
In a machine installation, a safety switching device for connecting and reliably disconnecting an electrical load in response to a switching event of a safety transmitter, said safety switching device comprising:a first input port for receiving a first input signal provided from said safety transmitter in correspondence to said switching event; an evaluation and control unit for evaluating said first input signal, said evaluation and control unit being capable of operating in one of at least three different operating modes; an operating mode selector unit for selecting an operating mode from said at least three different operating modes; at least one output switching element controlled by said evaluation and control unit for connecting and reliably disconnecting said electrical load, said output switching element being controlled as a function of the operating mode selected; a second input port for receiving a selector input signal, said selector input port being coupled to said operating mode selector unit for supplying said selector input signal; a signal generator for generating a group of at least three different reference signals; and a plurality of output ports coupled to said signal generator for providing said group of reference signals at said output ports; wherein one of said output ports is coupled to said second input port; wherein said operating mode selector unit comprises a comparator for comparing said selector input signal received with said at least three different reference signals for identifying the selector input signal received as one from the group of reference signals; and wherein said operating mode selector unit is adapted to select one of said at least three predefined operating modes in response to said selector input signal identified.