Large industrial machines benefit from this technology, in which Contrinex light curtains surround the working area with an infrared barrier. Compared with a physical barrier, much more useful space is left free and there is no reduction in visibility around the machine. Typical applications are metal cutting machines, printing systems, packaging and assembly lines. The YCA safety access control series comprises models with from 3 to 6 beams and beam-gaps of 300 mm, 400 mm, or 500 mm. They are suitable for detecting persons entering a dangerous area and bringing the potentially harmful machine cycle to a safe stop. Devices can operate across a distance of up to 50 meters and can also be used with mirror columns to create a protected perimeter. This technology is certified Type 4 by TUV according to IEC 61496-1 and -2 and ISO 13849-1. Users can also set the operating range to 15 m or 50 m simply by means of wiring configuration. Two communication channels are also available to avoid cross-talk when two pairs of light curtains are close to each other.