BL-USBMach3 controller board Index issue, not work, random RPM value

[wy6688]

I'm using BL-USBMach3 board for my 7x12 mini lathe, setting Pin 15 as index input, following same rule as Parallel breakout board.
but got random Spindle RPM value from 10-1000 RPM.

I have no problem with LPT breakout board.

Anyone have success with the BL-USBMach3 board to process Index input?

Thanks

[CitizenOfDreams]

What kind of tachometer do you have on your spindle? What kind of output does it have?

[wy6688]

I use Hall sensor A3144, it produce one pulse every revolution, it is very stable with parallel breakout board.