Abstract: A light curtain for use with a machine, such as a press brake. The light curtain includes a controller which is communicatingly connected to a controller of the machine, and at least one presence detector which is connected to the controller of the light curtain. The light curtain also includes at least one sensor which is configured to sense position and/or speed of movement of a moveable part of the machine, in use, the controller of the light curtain receives feedback from the at least one presence detector as well as from the at least one sensor which is configured to sense position and/or speed of movement of the moveable part of a machine. The controller of the light curtain signals the controller of the machine to operate the machine based on the feedback which is received by the light curtain.