RPM SENSOR (CNC12 Version 4.64 and above)

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RPM SENSOR (CNC12 Version 4.64 and above)

Post by martyscncgarage »

The CNC12 ACORN RPM SENSOR input option is to measure the RPM (Revolutions Per Minute) of a rotating assembly such as a Spindle.

This is done by triggering an Input on Acorn and assigning that input to RPM SENSOR.
The trigger signal must come in the form of an input that grounds the Acorn input at once per revolution. You are responsible to ensure that the circuitry used will provide Acorn with that ground input.

If your sensor is capable of grounding a 24VDC signal, you may connect it to any one of the Acorn inputs on H4 or H1. Using Acorn power supply COM as a reference. (Just like any other input like a limit or home switch)

If your sensor is only capable of grounding a 5VDC signal, you need to use one of the five DB25 Inputs,
on pins 10, 11, 12, 13 or 15 while using DB25 COM pins 18-25 as a reference. (NOTE: when an input is used on the DB25, the corresponding Input on Acorn can no longer be used. For example, if you connected your RPM sensor to DB25 Pin 10 (Input 1) you can no longer use INPUT 1 on Acorn as they are logically the same.

The sensor circuitry may include a Hall Effect Sensor, Optical Sensor, or Proximity Sensor which will trigger at once per rotation.

Please note, the purpose of RPM SENSOR is solely for the convenience of displaying RPM. It will not work for threading or rigid tapping To use those features, you must have a standard 5VDC Line Driver/Differential encoder coupled to the spindle with a timing belt at 1:1 and wired correctly to the Acorn DB9 Connector as well as Pro License

Please see the attached documents for reference. The Schematic (included in the latest Acorn Schematic Set) shows a typical connection for a hall effect sensor compatible with 5VDC signal.
RPM Sensor.JPG
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