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Simplified Chinese Spindle RPM Encoder
An incremental encoder is used to monitor spindle RPM and to enable synchronised threading on lathes.
| Pin No. | Description | Type |
|---|---|---|
| Pin 1 | Singal A | Opto input (5 to 24v) |
| Pin 2 | Signal B | Opto input (5 to 24v) |
| Pin 3 | Signal Z - Index | Opto input (5 to 24v) |
Spindle Encoder Signal
The A and B signals form a quadrature signal, meaning they are 90 degrees out of phase. MASSO uses these signals to determine spindle speed and direction.
The signal sequence is:
- A High, B Low
- A High, B High
- A Low, B High
- A Low, B Low
This sequence repeats continuously.
When the spindle rotates in the opposite direction, the sequence reverses.
The Z Index signal produces one pulse per spindle revolution.
This pulse is used on lathes to:
- Identify the starting point for threading
- Work with A and B signals to determine Z-axis movement during threading
Threading will not begin until the first Z index pulse is detected.
The A, B, and Z signals can be viewed on the F1 screen by slowly rotating the spindle by hand and observing:
- Encoder Signal A
- Encoder Signal B
- Encoder Index
If using the MASSO spindle encoder, the LED indicators on the encoder should match the signal states shown on the F1 screen.
MASSO Spindle Encoder turning in slow motion
Wiring Examples
Voltage Output Signal
Differential / Line Driver Output Signal
Maximum Encoder Frequency
To ensure the encoder frequency is within the MASSO limit, use the Encoder Frequency Calculator or calculate it manually using the provided formula.
Spindle Speed Encoder for Milling Machines
To display the actual spindle RPM, an encoder must be used.
Signals from the VFD represent the requested spindle speed, not the actual spindle speed.
If no encoder is installed but a speed display is required on the F2 screen, set the encoder PPR value to 0. This will display the commanded speed sent to the VFD.
If the spindle provides a pulsed output, or if an external encoder is installed:
- Connect the signal to the A spindle encoder input on MASSO G3
- Enter the encoder pulses per revolution (PPR) in the spindle settings (F1 screen)
The encoder inputs are optically isolated. The signal must be referenced to MASSO ground, as with all inputs.
