Safety circuit arrangement and method for the fail-safe monitoring of a movement variable

摘要

A safety circuit arrangement for the failsafe monitoring of a movement variable of a moving machine part has a signal input for supplying an encoder signal, with the encoder signal being representative of the movement variable to be monitored. The arrangement also has a reference signal path for supplying a reference signal, a tap connected to the signal input and to the reference signal path in order to provide a superposition signal by superposing the reference signal on the encoder signal, and a measuring unit which is connected to the tap and is designed to detect whether the superposition signal reaches at least one predefined signal level or is within a predefined signal level range.

主权项

1. A safety circuit arrangement for failsafe monitoring of a movement variable of a moving machine part, the arrangement comprising:
a first signal input for supplying a first encoder signal which is representative of the movement variable to be monitored, a first reference signal path for supplying a first reference signal, a first tap which is connected to the first signal input and to the first reference signal path in order to provide a first superposition signal by superposing the first reference signal on the first encoder signal, and a first measuring unit which is connected to the first tap and is designed to generate a first error signal depending on whether the first superposition signal reaches at least one first predefined signal level or is within a first predefined signal level range, a second signal input for supplying a second encoder signal which is representative of the movement variable, a second reference signal path for supplying a second reference signal, a second tap, at which the second reference signal is superposed on the second encoder signal, a second measuring unit which is connected to the second tap and is designed to generate a second error signal depending on whether the second superposition signal reaches at least one second predefined signal level or is within a second predefined signal level range, a differential amplifier having a first amplifier input connected to the first tap and having a second amplifier input connected to the second tap, an evaluation unit connected to an output of the differential amplifier for determining the movement variable, and a control unit designed to adjust the first and second reference signals separately from one another.