A system for controlling a process having a first control device for processing first data, and a first communication interface of a first communication unit designed for receiving the first data, and a second control device for processing second data, and a second communication interface of a second communication unit, designed for receiving the second data. The first communication unit comprises a third communication interface and the second communication unit comprises a fourth communication interface. The third communication interface is connected to the second communication interface and the first processor processes or compares the second data received by the third communication interface with the first data received by the first communication interface. The fourth communication interface is connected to the first communication interface, and the second processor processes or compares the second data received by the second communication interface with the first data received by the fourth communication interface.

A circuit is provided that has three clock sources, a first processing unit connected to the first clock source, a second processing unit connected to the second clock source, and an input unit. The first processing unit has a first logic circuit and a first memory circuit connected to the first logic circuit, wherein a first set of instructions, which is designed to implement a first control program when executed by the first logic circuit, is stored in the first memory circuit, wherein the first clock source specifies a clock timing of the execution of the first set of instructions. The second processing unit has a second logic circuit and a second memory circuit connected to the second logic circuit, wherein a second set of instructions, which is designed to implement a second control program when executed by the second logic circuit, is stored in the second memory circuit.

A process control system is provided which has at least one OPC client and one OPC server which communicate via a standardized OPC interface. Furthermore the process control system has at least two redundantly operated control devices which each communicate with the OPC server by means of a coupling device. Each control device is designed to provide process variables and status information. The status information contains the current role of the respective control device, wherein the current role is either that of a main control device or an auxiliary control device. The OPC server is designed to detect the main control device in response to the status information of at least one control device, to register a list of variables generated by the OPC client at the main control device and/or to transmit to the OPC client only the process variables which have been provided by the main control device.

A method for error-protected acquisition of a measured value in a control unit, wherein the measured value is firstly acquired with a first acquisition device and secondly with a second acquisition device and thereby a first measured value and a second measured value are made available, where in a comparison step in a safety program executing in the control unit, the first and the second measured value are compared with one another for a deviation from one another and upon reaching or exceeding a pre-determined maximum deviation, an error is identified.

A key switch on a machine control panel is provided with two contacts such that the machine control panel can include two independent communication circuits. Signals from a double-contact key switch are received by the two communication circuits, and safety-related signals are transmitted from the communication circuits to a numerical controller through a bus. The signals received by the numerical controller are compared with each other so that they can be made to comply with the safety standards by monitoring the integrity of the safety function.

A method and system for safely switching off an electrical load in a system comprising a multi-channel control unit, a single-channel data transmission path and an output unit having a first processing unit, a second processing unit and safe outputs. The method comprises receiving and evaluating an input signal by the multi-channel control unit and generating an enable signal based on the evaluation; transmitting the enable signal to the output unit via the single-channel data transmission path; receiving the enable signal by the first processing unit and generating an output signal based on the enable signal; providing at least one part of the enable signal from the first processing unit to the second processing unit for evaluation therewith; generating a dynamic clock signal by the second processing unit based on the enable signal; and controlling the safe outputs based on the output signal and the dynamic clock signal.

The invention relates to an engine control device comprising a first control channel (V1) and a second control channel (V2), each control channel comprising a first sensor (CAV1, CAV2) and a second sensor (CBV2, CBV2), each configured to provide, respectively, a first measurement (A) and a second measurement (B) to each channel, each of the channels having an active or passive state defining an active channel (V1) or a passive channel (V2), the active channel (V1) being designed to control at least one actuator (ACT) of the engine while the passive channel (V2) is designed to take over for the active channel if the latter fails.