A device for continuous control of a drilling hole depth in connection with rock and/or ground drilling using a drill device 5 mounted along a movable sled 4 which can be slid along a feeder beam 3. The device includes inductive units 9, 11 for generating counting pulses corresponding to the sled's 4 displacement along the feeder beam 3. These counting pulses are added to a counter 12 for the current drill hole depth by means of two connectors which are only connected if the drill device's 5 hammer works and, respectively, if the sled 4 exerts an essential feed force. Thus only the drill's net lowering will be recorded. IMAGE
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