Device, namely a coordinate measuring device or machine tool, having: • a displaceable device part, • a drive which is designed to drive the displaceable device part and thereby effect a displacement of the displaceable device part, • a control unit which is connected to the drive and is designed to control the drive, • a first signal transmitter to determine a position and/or speed of the displaceable device part, wherein the first signal transmitter and/or a first signal evaluation device connected to the first signal transmitter is connected to the control unit so that, during the operation of the device, the control unit receives information from the first signal transmitter relating to the position and/or speed of the displaceable device part and controls the drive depending on the information received, • a second signal transmitter to check and/or redundantly determine the position and/or speed of the displaceable device part, • a monitoring device which is designed to recognize an error of the device and/or a disruption to the operation of the device, taking account of signals of the second signal transmitter and/or information derived therefrom, characterized in that • the second signal transmitter has a signal transmitter unit which has a radiation source, a matrix of radiation-sensitive detector elements and a signal processor for processing detector signals of the detector elements, • the radiation source is designed to radiate radiation onto an element of the device displaceable in relation to the signal transmitter unit so that the matrix generates the detector signals depending on the relative position of the signal transmitter unit and the displaceable element, and • the monitoring component is connected directly or indirectly via at least one further component of the device to the signal processor. • a displaceable device part, • a drive which is designed to drive the displaceable device part and thereby effect a displacement of the displaceable device part, • a control unit which is connected to the drive and is designed to control the drive, • a first signal transmitter to determine a position and/or speed of the displaceable device part, wherein the first signal transmitter and/or a first signal evaluation device connected to the first signal transmitter is connected to the control unit so that, during the operation of the device, the control unit receives information from the first signal transmitter relating to the position and/or speed of the displaceable device part and controls the drive depending on the information received, • a second signal transmitter to check and/or redundantly determine the position and/or speed of the displaceable device part, • a monitoring device which is designed to recognize an error of the device and/or a disruption to the operation of the device, taking account of signals of the second signal transmitter and/or information derived therefrom, • the second signal transmitter has a signal transmitter unit which has a radiation source, a matrix of radiation-sensitive detector elements and a signal processor for processing detector signals of the detector elements, • the radiation source is designed to radiate radiation onto an element of the device displaceable in relation to the signal transmitter unit so that the matrix generates the detector signals depending on the relative position of the signal transmitter unit and the displaceable element, and • the monitoring component is connected directly or indirectly via at least one further component of the device to the signal processor.