Single-wire industrial safety system with safety device diagnostic communication

Patent metadata

Field	Value
Publication number	US-9841142-B2
Application number	US-201615187850-A
Country	US
Kind code	B2
Filing date	Jun 21, 2016
Priority date	Dec 22, 2014
Publication date	Dec 12, 2017
Grant date	Dec 12, 2017

Abstract

A single-wire safety system architecture is provided that yields reliable safety device monitoring without the need for dual redundant signal channels. The safety system comprises a safety relay acting as a communications master device and one or more compatible safety devices connected in series with the safety relay via a single-wire communication circuit. The safety device farthest from the safety relay on the safety circuit modulates a safety signal with a recognizable pulse pattern that traverses the single-wire safety circuit to the safety relay via the intermediate safety devices. The safety relay maintains safety mode as long as the pulse pattern is received and recognized. The architecture allows bi-directional communication of initialization, configuration, and diagnostic messages over the single-wire safety channel, and can also allow safety devices to insert prognostic data into the safety signal in order to convey health information while the system is in normal operation mode.

First claim

What is claimed is:

1. A safety device, comprising:
a memory that stores executable components;
a processor, operatively coupled to the memory, that executes the executable components, the executable components comprising:
a safe state detection component configured to determine whether the safety device is in a safe state;
a pulse detection component configured to verify that a modulated pulse pattern contained in a safety signal portion of a safety signal received on an input terminal of the safety device corresponds to a defined pulse pattern;
a status word control component configured to write device status data to a device data portion of the safety signal; and
a safety signal relaying component configured to output the safety signal on an output terminal of the safety device in response to verification that the modulated pulse pattern corresponds to the defined pulse pattern and a determination that the safety device is in the safe state.

2. The safety device of claim 1 , the executable components further comprising a message processing component configured to process a first input message received via the input terminal, to process a second input message received via the output terminal, to send a first output message via the input terminal, and to send a second output message via the output terminal.

3. The safety device of claim 1 , wherein the device data comprises prognostic data generated by the safety device and an address of the safety device.

4. The safety device of claim 3 , wherein the status word control component is further configured to write the device status data to the device data portion in response to a determination that a previous device data portion of the safety signal that was output on the output terminal during a previous cycle of the safety signal contained another address for another safety device that is one unit higher than the address of the safety device.

5. The safety device of claim 1 , wherein respective cycles of the safety signal comprise the safety signal portion and the device data portion separated by a separation gap having a defined duration.

6. The safety device of claim 1 , wherein the safety signal relaying component is further configured to invert the modulated pulse pattern prior to outputting the safety signal on the output terminal.

7. The safety device of claim 1 , wherein the safety device is configured to, in response to receiving, via the output terminal, a configuration message identifying one of multiple defined pulse patterns, configure the pulse detection component to recognize the one of the multiple defined pulse patterns as the defined pulse pattern.

8. The safety device of claim 1 , wherein the safety device comprises a mechanical actuating component, and is configured to control an actuation of the mechanical actuating component based on a supplemental signal received via a supplemental input terminal of the safety device.

9. The safety device of claim 1 , wherein the safety device is configured to
in response to receiving, within a defined time period after initiation of a startup sequence, one of a response message from a first safety device via the input terminal or a device present message from a second safety device via the output terminal, enable the pulse detection component, the status word control component, and the safety signal relaying component, and
in response to the defined time period expiring without receiving one of the response message or the device present message, disable the pulse detection component, the status word control component, and the safety signal relaying component, and configure the input terminal and the output terminal to operate as standard safety output terminals.

10. The safety device of claim 1 , wherein the safety input device is at least one of an emergency stop pushbutton, a light curtain device, a safety door switch, a safety mat device, an emergency pull-cord device, a laser scanner, a photoelectric sensor, a safety contactor, a proximity switch, or a safety edge device.

11. A method for operating a safety device on a safety circuit, comprising:
determining, by a safety device comprising a processor, whether the safety device detects a safe status;
comparing, by the safety device, a defined pulse pattern with a pulse pattern carried by a safety signal portion of a safety signal received on an input terminal of the safety device;
writing, by the safety device, device status data to a device data portion of the safety signal; and
in response to determining that the pulse pattern matches the defined pulse pattern based on the comparing and that the safety device detects the safe status, outputting, by the safety device, the safety signal via an output terminal of the safety device.

12. The method of claim 11 , further comprising:
processing, by the safety device, a first input message received via the input terminal;
processing, by the safety device, a second input message received via the output terminal;
sending, by the safety device, a first output message via the input terminal; and
sending, by the system, a second output message via the output terminal.

13. The method of claim 11 , wherein the writing comprises writing an address of the safety device and prognostic data relating to a condition of the safety device.

14. The method of claim 13 , wherein the writing comprises:
determining that a previous device data portion of the safety signal that was output on the output terminal during a previous cycle of the safety signal contained another address for another safety device that is incremented by one relative to the address of the safety device; and
writing the device status data to the data portion in response to the determining.

15. The method of claim 11 , wherein the outputting comprises inverting the pulse pattern carried by the safety signal portion prior to outputting the safety signal via the output terminal of the safety device.

16. The method of claim 11 , further comprising:
receiving, by the safety device via the output terminal, a configuration message identifying one of multiple defined pulse patterns; and
designating, by the safety device in response to the receiving, the one of the multiple defined pulse patterns as the defined pulse pattern.

17. The method of claim 11 , further comprising controlling, by the safety device, an actuation of a mechanical actuation component of the safety device in accordance with a supplemental signal received via a supplemental terminal of the safety device.

18. The method of claim 11 , further comprising:
initiating, by the safety device, a startup sequence;
initiating, by the safety device, a timer having a defined timeout duration;
in response to receiving, prior to expiration of the timer, one of a response message from a first safety device via the input terminal or a device present message from a second safety device via the output terminal, enabling, by the safety device, the comparing, the writing, and the outputting, and
in response to the timer expiring without receiving one of the response message or the device present message, disabling, by the safety device, the comparing, the writing, and the outputting, and configuring the input terminal and the output terminal to operate as standard safety output terminals.

19. A non-transitory computer-readable medium having stored thereon instructions that, in response to execution, cause a safety device comprising a processor to perform operations, the operations comprising:
determining whether t

Assignees

• Rockwell Automation Tech Inc

Inventors

• Nair Suresh R
• Foster Wayne R
• Harris Alex
• Papenbreer Rudolf Laurenz
• Machuletz Norbert
• Heckel Oliver
• Helpenstein Thomas
• Duros Van

Classifications

• F16P3/00 Primary

  Safety devices acting in conjunction with the control or operation of a machine; Control arrangements requiring the simultaneous use of two or more parts of the body (F16P5/00 takes precedence) · CPC title

• G05B9/02

  electric · CPC title

• G05B19/0425 Primary

  Safety, monitoring · CPC title