Abstract: An expansion module for an industrial controller is configured to perform independent local processing of its input signals and to independently generate control outputs in parallel with the primary control program executed by the industrial controller. This can reduce or eliminate response latency for time-critical processes that would otherwise be present if all monitoring and control were performed by the industrial controller alone. This approach can be beneficial for configurations in which the industrial devices that are monitored and controlled via the expansion module require fast response times, as in the case of industrial safety applications.

Abstract: A single-wire safety system architecture yields reliable safety device monitoring without the need for dual redundant signal channels. The safety system comprises a safety relay and one or more compatible safety input devices connected in series with the safety relay via a single-wire communication circuit. A safety signal with a recognizable pulse pattern traverses the single-wire safety circuit to the safety relay via the safety devices. The safety relay opens its contactors and deenergizes its associated industrial equipment if the pulse pattern is not received and recognized. The safety relay can also be configured to initiate a global emergency stop in response to a loss of a safety function by one of its safety input devices, the global emergency stop instructing other safety relays of other safety circuits to open their contactors and enter safe mode.

Abstract: A safety input device for use in a single-wire safety system comprises a fast-switching architecture that allows a safety signal to propagate through the safety device to downstream devices with negligible delay. Rather than placing the signal processor in-line between the signal input and output terminals of the safety device, an electronic switch is placed between the input and output terminals. A signal processor in parallel with the switch monitors the incoming signal and closes the switch if the safety signal is absent, effectively shorting the input and output terminals and allowing the incoming safety signal to pass substantially instantaneously. Loss of the safety signal at the input terminal is immediately reflected by the loss of safety signal output at the output terminal, eliminating processing delay between loss of the safety signal at the input terminal and cessation of the output signal at the output terminal.

Abstract: A single-wire safety system architecture yields reliable safety device monitoring without the need for dual redundant signal channels. The safety system comprises a safety relay and one or more compatible safety input devices connected in series with the safety relay via a single-wire communication circuit. A safety signal with a recognizable pulse pattern traverses the single-wire safety circuit to the safety relay via the safety devices. The safety relay opens its contactors and deenergizes its associated industrial equipment if the pulse pattern is not received and recognized. The safety relay can also be configured to initiate a global emergency stop in response to a loss of a safety function by one of its safety input devices, the global emergency stop instructing other safety relays of other safety circuits to open their contactors and enter safe mode.

Abstract: An expansion module for an industrial controller is configured to perform independent local processing of its input signals and to independently generate control outputs in parallel with the primary control program executed by the industrial controller. This can reduce or eliminate response latency for time-critical processes that would otherwise be present if all monitoring and control were performed by the industrial controller alone. This approach can be beneficial for configurations in which the industrial devices that are monitored and controlled via the expansion module require fast response times, as in the case of industrial safety applications.