MachPro Spindle Configure for M31 up to Rev 1.2

Analog 0-10V and sinking outputs for spindle control

M31 Motion Controllers prior to Rev 1.3 use sinking outputs to control the CW and CCW direction of rotation on the spindle.

Using 0-10VDC to control the speed, and sinking outputs to control the rotation direction of the spindle

M31 Spindle features
Opto-Isolator Outputs	Forward and Reverse Open Drain / Open Collector outputs
Analog Speed Signal	0-10VDC
Encoder Feedback	Yes

M31 to VFD Direction Control – Field Wiring Guide

This section explains how to wire the M31 motion controller to a VFD (Variable Frequency Drive) for Forward and Reverse control.

The language here uses standard sinking and sourcing terms used by field technicians.

Key facts about the M31 outputs

The M31 always uses sinking outputs.
The Forward and Reverse outputs are optocoupled.
Each output has an NPN sinking optocoupler to 0 V COM.
When an output turns ON, it connects the VFD input to 0 V COM and sinks current.
When an output turns OFF, the circuit is open and no current flows.

Sinking vs sourcing – basic idea

A sourcing device provides +24 VDC to the circuit.
A sinking device connects the circuit to 0 V COM to let current flow.
The M31 is a sinking device.
The VFD digital inputs usually act as sourcing inputs when configured for sinking-mode wiring.

What the VFD actually senses

The VFD digital inputs sense current, not the 24 VDC level.
The 24 VDC from the VFD is only a power source for the input circuit.
The VFD decides ON or OFF by checking whether current flows into the digital input.
If current flows, the input is active (Forward or Reverse commanded).
If no current flows, the input is inactive (no command).

How VFD digital inputs should be configured

Most VFDs allow different wiring modes for digital inputs.

For use with the M31:

Configure the VFD digital inputs for sinking-type wiring.
In manuals, look for terms like:
- “Sink input”
- “NPN input”
- “Sinking (NPN) logic”
- “0 V common for digital inputs”
- “Digital inputs referenced to 0 V”

Avoid modes described as:

“Source input”
“PNP input”
“24 V common for digital inputs” (where inputs switch to +24 V)

These modes are intended for sourcing outputs, not the M31.

Role of the VFD’s 24 VDC control supply

The VFD normally provides a 24 VDC control supply terminal.
The VFD routes this 24 VDC to each digital input circuit.
The 24 VDC exists only to allow current to flow through the input and the M31 output.
The VFD’s decision is based on current presence, not on “seeing 24 VDC”.

Forward and Reverse OFF (no command)

When both M31 Forward and M31 Reverse outputs are OFF:

Both optocoupled outputs are open circuits.
No current flows from the VFD’s 24 VDC supply through the Forward input.
No current flows through the Reverse input.
The VFD reads:
- Forward input = OFF
- Reverse input = OFF
The VFD sees no direction command.

Forward ON – sinking current

When the M31 Forward output turns ON:

The VFD supplies 24 VDC to the Forward digital input circuit.
The VFD Forward digital input connects to the M31’s Forward Collector (FC).
The M31 closes the path between collector and emitter in the Forward output.
The emitter connects to 0 V COM.
Current flows:
VFD 24 VDC → M31 Forward Collector (FC)→ M31 Forward emitter (FE) → 0 V COM
The M31 is sinking this current.
The VFD senses this current flow and interprets it as Forward = ON.

Reverse ON – sinking current

When the M31 Reverse output turns ON:

The VFD supplies 24 VDC to the Reverse digital input circuit.
The VFD Reverse digital input connects to the M31’s Reverse collector (RC).
The M31 closes the path between collector and emitter in the Reverse output.
The emitter connects to 0 V COM.
Current flows:
VFD 24 VDC → M31 Reverse Collecter (RC)→ M31 Reverse emitter (RE) → 0 V COM
The M31 is sinking this current.
The VFD senses this current flow and interprets it as Reverse = ON.

Wiring checklist for field technicians

When wiring a VFD to the M31:

Find in the VFD manual:
- 24 VDC control supply terminal.
- 0 V COM (or “DC-”, “CM”, “COM”) terminal.
- Digital input terminals for Forward / Run and Reverse.
- Digital input mode settings related to sink / source / NPN / PNP.
Configure the VFD digital inputs for:
- Sink / NPN / sinking logic mode.
- Inputs referenced to 0 V COM.
Wire the control supply and commons:
- Connect VFD 0 V COM to M31 FE and RE.
- Use the VFD’s 24 VDC as the field control supply for its inputs.
Wire the direction signals:
- Connect the VFD Forward input to the M31 Forward collector (FC) terminal.
- Connect the VFD Reverse input to the M31 Reverse collector (RC) terminal.
Verify operation:
- Command Forward from the M31 and confirm the VFD sees Forward ON.
- Command Reverse from the M31 and confirm the VFD sees Reverse ON.

Summary

The M31 always uses sinking outputs for Forward and Reverse.
The VFD senses current, not 24 VDC level.
Set VFD digital inputs to sink / NPN / sinking logic mode.
The VFD sources 24 VDC, and the M31 sinks current to 0 V COM to signal direction.

For 0-10VDC speed control, look for Analog Inputs (AI) and 0VDC connections on the VFD.

Analog Inputs: AI1, V1, AVI

0 volt: AC, 0V, ACM, GND

For direction control look for, or configure the Forward and Reverse digital control inputs on the VFD. This will also need a 0VDC connection.

Digital Inputs: S1, FWD, S2, REV,

0 volt: SN, SC, DCM

This is an example connecting the M31 to a Yaskawa GA500 VFD. Please refer to the documentation for your VFD.

M31 Motion Control	Yaskawa GA500 VFD
0-10VDC speed control	A1
0VDC	AC
Forward Collector (sinking)	S1 (forward by default)
Reverse Collector (sinking)	S2 (reverse by default)
Forward Emitter	SC (common)
Reverse Emitter	SC (common)

Here is a diagram showing the electronic circuit of the M31 on the Emitter and Collector signals: