Omron Photo Microsensors
Dimensions and wiring.

Home sensors are highly recommended on all shutter axis (camera, projectors, fader), and are advisable but not mandatory for translation axes (North/South, East/West, Zoom).

This diagram shows how to wire an IBM PC parallel port to an Omron OR508ND home sensor. Note that up to four home senors can be monitored by each parallel port. You can also use the Kuper Logic Connector to accept more sensor inputs.

The Omron OR508ND or equivalent microsensors are available from DigiKey 1-800-344-4539. The ordering information supplied below are DigiKey prices as of April 1995, which have probably changed by now.

Description Digikey Part# Price
Omron OR508ND Microsensor OR508ND $8.97
4 Pin connector for the above OR527ND $1.90
    Update (07/17/98): According to the folks at Omron, the OR508ND has been replaced with the EE-SX670, DigiKey part number OR528-ND. This is an amplified photomicrosensor with similar connections. Refer to the Digikey catalog for more information.

Purchasing Comments

  • If you need 8, buy 10. It's good to have a few extra, incase you trash a couple during mounting.

  • Buy a few extra 4 pin connectors, incase you melt a few.

  • Don't forget to buy pullup resistors. 220 to 440 ohms are recommended.

Wiring Comments

  • Use the 'parallel.exe' program that comes with OPCS to test home sensors connected to the parallel port, or use the '8255.exe' program for sensors connected to a generic 8255 programmable I/O card, or use the 'kuper.exe' program for sensors connected to the Kuper Logic Connector.

    These programs have a little 'logic osciliscope' and sound cues that lets you easily debug problems with home sensor inputs to the computer.

      Note: under OPCS, the RTMC-16 logic connector should only be used for inputs; do *not* use it for outputs, since the port is write only, which confuses programs that expect to be able to read the bits as well. With the RTMC-48, do not use the kuper logic connector at all, neither for inputs or outputs; it does not support port read/writes in a single I/O operation.

  • Be sure to use shielded cable, and ground the shield at a common grounding point at the chassis. Make sure your chassis is properly grounded.

  • Make sure your 5 volt supply is properly isolated from inductive devices, to prevent back-currents to the computer.

  • When running the home sensors wires, do NOT bundle them with the motor drive wires, to avoid noise/crosstalk problems.

  • Use an oscilliscope to monitor the home sensor signals at the computer while motors are running to check for potential crosstalk.

Dimensions are in milimeters. 4 pin connector (OR527ND) not shown.

© Copyright 1997, Greg Ercolano. All rights reserved. To report documentation errors, send email to