Mesa 7i92TF Gecko G540 Spindle Encoder Issues

16 Mar 2024 22:08 #296100 by Burf
I have a Taig mill driven by a G540 that I've been working on upgrading to LinuxCNC with a Mesa 7I92TF . I've been able to get all axes working with the Mesa board, but I'm struggling to get my spindle tachometer to work. I'm new to LinuxCNC and am a little stuck on determining if this is a hardware issue with the Mesa board or a .hal file issue. Before upgrading to the 7I92TF I had the spindle tachometer working well and displaying RPM in LinuxCNC with the control computer parallel port connected directly to the G540, so I know the tachometer is working as intended.

The spindle tachometer is this DIY design that provides a single pulse per revolution on one wire. It behaves like a limit switch where when the tach is triggered the signal wire is shorted to ground. For the attached .hal files I have the encoder signal wire hooked up on pin 10 of the G540. For both HAL files I think that pin should correspond to phase A of the encoder. Also attached is the readhmid output for the 7I92TF.

Using Halmeter and Halscope I've never been able to see spindle-phase-a change using the Mesa board when turning the spindle, but if I pull the tach signal wire out of the G540 the Halmeter readout of spindle-phase-a will go from false to true. If I tap the signal wire against the G540 terminal block associated with pin 10 I get an RPM reading in the GUI as if the tach was reading. This behavior is the same regardless of if the tach is in the triggered or non-triggered state while I tap the wire on the G540. This leads me to think there's an issue with the configuration of the 7I92TF, but I'm not sure what it could be. I've used a multimeter to verify the tachometer is shorting the signal wire to ground as expected, and also hooked the parallel port setup back up several times and observed the RPM readout works.

Jumper Positions on the Mesa board are:
W1: Up
W2: Up
W3: Down
W4: Down
W5: Down
W6: Up

I have also tried setting W1 and W2 to down with no luck.

Any insight would be much appreciated!

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16 Mar 2024 22:52 #296102 by PCW
That really does no make much sense if physically grounding the G540 input
works but you sensor input doesn't. There may be a difference in that a parallel
port configuration would share a common ground with the PC but a 7I92 config may

Also if this is intended for spindle synchronized motion, you would need to go back to the
software encoder as the hardware encoder will not support using 1 pin for A and Z

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