No chance to use outputs on P1 MESA 7i92 help needed.

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24 Sep 2026 15:40 - 24 Sep 2026 15:50 #349840 by muddiver
Hi folks!
i'm trying to find my way getting anything to work.

Whats fine: Handwheel / MPG works, the encoder-Pins are on P1 of the MESA, which is working fine.
Machineaxis running fine, reference-switches work fine,
Funfact, The PWM-pin and the encoderpins on P1 are working, which gives me the feeling i forgot to setp something to get the outputs to work..

My Problem: I have a VFD which i wanted to control via LinuxCNC.
The PWM-Pin works fine, i have a 0-10V Card connected to it, that's fine.
But all my outputs to start the VFD or stop it, absolutely no reaction to my commands..

I have a cheap Mach3 Breakoutboard, which sets it's Outputs to 3Volts when nothing is connected, so i started to measure my way to the MESA-Card. At first i thought it is a Pulldownresistor story, but that changed nothing too..

Finally, my outputs 19 / Pin 2 DB25 and 21 / Pin 3 DB25 of the MESA-Card are always 5Volts, when i connect a Pulldown-resistor 1k to ground, i see 0,8V .
I can toggle these outputs ( when commenting out the usage in HAL ) via halshow ui, but still i see 5V. 0,8 if connected to the resistor.
No reaction.

I attached my konfig, and my Pinfile which is on flashed on the card, i had to rename it to txt for the upload..
The HAL-File for the VFD is named "bzt-fu.hal" , all the addf and loadrt commands are transfered to the custom.hal.I commented these out in the halfiles where they came from, just to make it easy to remember from where the loadrt or addf commands are coming from.

I start thinking i somehow fried the card.. Help welcome!
Greets, Tom
Last edit: 24 Sep 2026 15:50 by muddiver.

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24 Sep 2026 15:47 - 24 Sep 2026 15:52 #349841 by muddiver
And just because i measured a lot, are all outputs Pull-Up's?
Do i need an Pulldown-resistor to make the card work? 

Strange behavior with the attachments, the files somehow have a date added..   The Bitfile is attached her..
Attachments:
Last edit: 24 Sep 2026 15:52 by muddiver.

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24 Sep 2026 18:11 #349845 by tuxcnc
setp hm2_7i92.0.gpio.019.is_output 1

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24 Sep 2026 22:07 #349851 by rodw
A couple of photos would help as I don't understand what you have done
Normally you would use 0-10 volt from the VFD itself.
Your VFD will have several terminals on it that need their function set, I have X1,X2,X3,X4 that can be programmed for specific functions
A 5v relay either on your BOB  or an external one will trigger forward and reverse. (I used X1,X2)
The VFD should also have a relay internally. You can program this to be "Frequency reached" or similar and send that back to LinuxCNC for your at speed signal.
The only catch I  had was I had to invert the pwm pin otherwise it ran the wrong way (eg S0 gave 10 volts). Not sure how Mesa does it. I recently published some videos on my YouTube @MrRodW channel about wiring in a BOB and how to set up the spindle.

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