An incremental encoder is used to monitor spindle RPM and also for synchronized threading on lathes.

Spindle Encoder Signal

The A & B signals is a Quadrature signal, ie 90 degrees out of phase with one another. MASSO can use this signal to determine speed and which direction the spindle is turning.

The A, B signal sequence runs as follows.

• A - High B - Low
• A - High B - High
• A - Low B - High
• A - Low B - Low

The sequence repeats.

The sequence will reverse if the spindle is run in the opposite direction.

The Z Index signal outputs a pulse once every rotation of the Spindle.

The Index pulse is used on Lathe to determine the start of threading and is used in conjunction with the A & B pulses to determine the Z axis speed during the Threading cycle.

Threading will not proceed until the first Z pulse is received.

The A, B & Z pulses can be seen on the F1 Screen by slowly turning the spindle by hand and observing the Encoder Signal - A, Encoder Signal- B and the Encoder Index signals.

If using the MASSO Spindle Encoder the LED indications on the encoder should match the high and lows shown in the F1 Screen.

MASSO Spindle Encoder turning in slow motion

INFORMATION: The maximum pulse frequency on encoder inputs for MASSO G3 controllers is 60kHz.

INFORMATION: All input signals can be easily inverted by selecting the input in the INPUTS list and pressing the space-bar key on the keyboard to invert the input signal. These settings are automatically saved.

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Maximum Encoder Frequency

To confirm that the encoder frequency will be within the Masso maximum pulse frequency please use the Encoder Frequency Calculator

Encoder Frequency Calculator

Or you can manually calculate it using the formula below.

INFORMATION: For information on the MASSO encoder and printing a custom encoder disk please see here: https://docs.masso.com.au/index.php/wiring-and-setup/setup-and-calibration/masso-optical-encoder

Spindle speed Encoder for Mill

To see the actual RPM of your Spindle you must to use an encoder.

Speed signals taken direct from the VFD indicate the requested spindle speed it receives from MASSO and not the actual spindle speed

If you do not have an encoder installed on your spindle but wish to see a speed indication on the F2 screen, setting the Encoder (Pulses per revolution) value to 0 will show the speed sent to the VFD.

If your Spindle includes a pulsed output or you have an external encoder, you can connect this to the A spindle encoder input of your G3.

MASSO can use this to display the spindle speed.

In the Main Spindle set up page in the F1 screen enter the encoder pulse per revolution output by your spindle.

The spindle encoder inputs are optically isolated like the rest of MASSO inputs. You need to have the pulse signal referenced to MASSO ground as with all input signals.