Safety control for the secure operation of a technical plant and method of operating a safety control

• US 10,114,345 B2
• Filed: 04/06/2015
• Issued: 10/30/2018
• Est. Priority Date: 04/25/2014
• Status: Active Grant

• Current Assignee: Sick AG (Sick)
• Original Assignee: Sick AG (Sick)
• Inventors: Saumer, Markus
• Primary Examiner(s): Bahta, Kidest
• Application Number:
  US14/679,591
• Publication Number:
  US 20150309481A1
• Time in Patent Office: 1,303 Days
• CPC Class Codes: G05B 9/02 electric

Abstract

In order to reduce the power-loss in digital inputs of a safety control, a safety control for the secure operation of a technical plant is provided that comprises at least one input unit for the reception of a signal of at least one signal generator connected to the technical plant, a control unit for the reading in of the received signal and for generating a control command, and at least one output unit for the transmission of the generated control command to at least one connected actuator of the technical plant, wherein the input unit has a switching element at the input side that can be controlled by means of the control unit and is configured in such a way that the switching element can be actuated by means of the control unit directly prior to the reading in of the received signal, in particular can be closed, and can be actuated again by means of the control unit, in particular opened, following the reading in of the received signal.

Claims

1. A safety control for the secure operation of a technical plant, comprising:

at least one input unit which receives a signal of at least one connected signal generator of the technical plant;

a control unit, comprising a CPU, for reading in the received signal and for generating a control command; and

at least one output unit which transmits the generated control command to at least one connected actuator of the technical plant,

wherein the input unit has a switching element at an input side thereof, the switching element connecting the at least one connected signal generator of the technical plant to the control unit, the switching element being periodically controlled at intervals discrete in time by means of the control unit and is configured in such a way that the switching element is actuated by means of the control unit by closing directly prior to the reading in of the received signal and actuated again by the control unit by opening after the reading in of the received signal, the at least one input unit receiving the signal of the at least one connected signal generator of the technical plant via the switching element at the input side of the at least one input unit.

2. The safety control in accordance with claim 1, wherein the switching element is closed by the control unit directly prior to the reading in of the received signal and is opened by the control unit after the reading in of the received signal.

3. The safety control in accordance with claim 1, wherein the switching element is one of an electronic switch and an electromechanical switch.

4. The safety control in accordance with claim 1, wherein the signal generator is an optoelectronic sensor, or an emergency cutoff function.

5. The safety control in accordance with claim 1, wherein the control unit is configured to determine a state of the input unit from an actuation of the switching element.

6. The safety control in accordance with claim 5, wherein the actuation of the switching element comprises closing and opening.

7. A method of operating a safety control having at least one input unit which receives a signal of at least one connected signal generator of a technical plant, a control unit for reading in the received signal and for generating a control command and at least one output unit which transmits the generated control command to at least one connected actuator of the technical plant, wherein the method comprises the steps of:

transmitting the signal of the signal generator to the input unit and actuating a switching element arranged at the input side of the input unit to close the switching element at periodic intervals discrete in time to close the switching element at periodic intervals discrete in time to read in the signal; and

actuating the switching element again thereafter to open the switching element, to separate the input unit from the signal generator, the switching element connecting the at least one connected signal generator of the technical plant to the control unit, the at least one input unit receiving the signal of the at least one connected signal generator of the technical plant via the switching element at the input side of the at least one input unit.

8. The method in accordance with claim 7, wherein the switching element arranged at the input side of the input unit is closed such that the signal is read in and opened again thereafter such that the input unit is separated from the signal generator.

9. The method in accordance with claim 7, wherein the switching element is periodically actuated by the control unit.

10. The method in accordance with claim 7, wherein the switching element is closed and opened by the control unit at intervals discrete in time.

11. The method in accordance with claim 7, wherein the control unit compares a state of the switching element on closing and opening and therefrom determines a secure error-free operating readiness of the switching element and of the input unit.

12. The method in accordance with claim 11, wherein, following the switching on or switching off of the switching element respectively, the control unit determines an error of the switching element or of the input unit respectively, when a signal level, a status indication of the switching element and/or of the input unit remains unchanged.