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MachPro Tool Setter Wiring and Configuration

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NO probing with NC overtravel

Scope

This document describes how to wire a PHM2P (P) probe to a CNC controller and how to configure two controller inputs:

  • Probe trigger input (Normally Open output).

  • Overtravel alarm input (Normally Closed output).

Definitions

  • DC: Direct current.

  • 0 VDC: Power return for the 24 VDC supply (also called DC common).

  • NO (Normally Open): The contact is open in the normal state. It closes when the probe triggers.

  • NC (Normally Closed): The contact is closed in the normal state. It opens during an overtravel alarm.

  • Dry contact: A relay contact that does not supply voltage. The controller (or an external supply) provides the input voltage.

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How-to guide

1) Wire power (24 VDC)

  1. Connect RED to +24 VDC.

  2. Connect GRAY to 0 VDC.

2) Wire the probe trigger (NO contact) to a controller input

The probe trigger uses the BROWN–ORANGE pair. This is a dry NO contact.

Choose one method that matches your input style.

Method A: Input turns ON when it receives +24 VDC (common 24 V field inputs)

  1. Connect +24 VDC to BROWN (or ORANGE).

  2. Connect the other wire (ORANGE or BROWN) to the controller input terminal (example: PROBE).

  3. Wire the controller input common (COM) as the controller manual specifies.

Method B: Input turns ON when it is connected to 0 VDC

  1. Connect the controller input terminal (example: PROBE) to BROWN (or ORANGE).

  2. Connect the other wire (ORANGE or BROWN) to 0 VDC.

  3. Wire the controller input common (COM) as the controller manual specifies.

3) Wire the overtravel alarm (NC contact) to a second controller input

The overtravel alarm uses the GREEN–BLUE pair. This is a dry NC contact.

Wire it the same way as an input contact, but configure the controller so an open circuit causes an alarm (failsafe).

4) Configure the controller for NO probing with NC overtravel

A) Probe input (NO)

Set the probe input so the normal state is not triggered, and the triggered state occurs when the contact closes.

  • Function: Probe / Touch probe / Skip signal (use the controller’s probe function).

  • Normal state: OFF.

  • Triggered state: ON.

  • Invert / Active-low setting:

    • If you used Method A (contact applies +24 V when triggered): Invert = OFF (Active-high).

    • If you used Method B (contact applies 0 V when triggered): Invert = ON (Active-low).

Optional:

  • Input filter / debounce: enable a small filter if your controller supports it (use the minimum value that stops false triggers).

B) Overtravel input (NC, failsafe)

Set the overtravel input so the normal state is healthy, and an open contact causes a fault.

  • Function: Overtravel / Alarm / External fault (use a fault-capable input).

  • Normal state: ON (healthy).

  • Alarm state: OFF (fault).

  • Invert / Active-low setting:

    • Configure as “Normally Closed” if the controller has that option.

    • If the controller only has “Invert,” set it so an open circuit = fault.

  • Fault action: stop motion and require reset (as supported by the controller).

5) Test

  1. Power the probe (24 VDC).

  2. Check the probe input status on the controller:

    • Normal: probe input is not triggered.

    • Touch the probe: probe input becomes triggered.

  3. Check the overtravel input status:

    • Normal: overtravel input is healthy.

    • Simulate overtravel (or open the circuit briefly): controller shows fault.

Reference

Wire functions

  • RED: +24 VDC supply

  • GRAY: 0 VDC return

  • BROWN + ORANGE: Probe trigger output, dry contact, NO

  • GREEN + BLUE: Overtravel alarm output, dry contact, NC

  • Cable: Oil-resistant, 6-core

Rated specifications (selected)

  • Output mode: NO (probe trigger)

  • Trip (pre-travel): 5 mm

  • Repeat accuracy: 0.001 mm at 50 to 200 mm/min

  • Contact life: 3,000,000 operations

  • Protective structure: IP67 (dust-tight, temporary immersion)

  • Contact force: 1.5 N (install vertically)

  • Contact rating: 24 VDC, 20 mA maximum (recommended 10 mA, resistive load)

  • Tool surface: cemented carbide, mirror polishing 4S

  • Tool face diameter: 20 mm or 40 mm

  • Installation hole distance: 40 mm

Note: If you have multiple datasheets, use the lowest contact-current rating when you design the input circuit.

Explanation

Why use NC for overtravel

An NC alarm circuit is failsafe. If a wire breaks or a connector loosens, the circuit opens and the controller sees a fault.

Why the output is called a dry contact

The probe does not source voltage from the output wires. The output only opens or closes a contact. The controller input circuit must supply the sensing voltage.

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