BEI Sensors

Optical Isolator Interface


This versatile interface between a sensor and any receiving electronics provide an electrically robust output to the receiving electronics. This presents a solid solution for systems with poor signal compatibility, noise and/or grounding problems.

By providing a clean interface between the sensor and the receiving electronics, the optical isolator can be used to:

  • eliminate ground loops
  • reduce signal degradation from long cable runs (by acting as a repeater)
  • distribute an sensor signal to multiple input devices

It accepts single ended or differential inputs and provides single ended or differential outputs in either an open collector or line driver configuration. It accommodates all standard operating voltages from 5 to 28 VDC.

Up to eight Optical Isolator Modules can be daisy-chained to provide multiple, simultaneous outputs to controllers or PLC’s. The Optical Isolator can help clean up noisy signals by converting to a differential line driver output. It has a 1 MHz throughput capability and can be used wherever a fast, optically isolated interface is required.

Resolve Electrical Interference
Various photo-detectors were being used in a conveyor system as event triggers and for inspection purposes. As the system grew and became more complicated, the controllers were starting to experience some electrical interference.

The photo-detectors had single ended open-collector style outputs operating at 5 volts. By routing these to the input channels of the Optical Isolator Module they were then converted to differential line driver outputs at 24 volts. The higher voltage level combined with the differential output (the system was changed to differential receivers as well) made this interference problems go away.

A lumber mill processing line had several segments that were already automated, and worked quite well. The mill started to integrate these automated portions of the mill with the new controls. In order to synchronize the 'gripper' with the conveyor, the feedback signals from a single encoder needed to be used for several separate PLC's. Unfortunately the PLCs required various types of inputs. And to complicate matters more, one of the PLC's had a 'funny' noise problem, which the mill suspected a ground loop.

By using BEI's optical isolator modules, the mill was able to daisy chain the output from his single encoder to both modules and then match the output characteristics of each of the modules to their respective PLC's.

On extremely long cable runs (greater than 500 feet), an optical isolator module can be used as a mid-point repeater to receive, amplify and re-broadcast the signal.

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