[mactec54]

well I only get a 5V "swing". So if I have the adjustment pot set to it's min, the max output i'll get is 5V. If i adjust the pot up, I can get the full 10V output, but it'll never go below 5V.

I have it hooked up to a 12V power supply as well.

I'm trying to find someone with an oscilloscope to see what input frequency is as i adjust the commanded spindle speed. I think that'll at least tell me if it's a hardware issue or software, but i'm open to any thoughts .

Is there a jumper on the Board that you have to change for 0-5v or 0-10v output this C6 is stand alone so if it is working then it is something to do with the C6, the supply signal needs to be 25Khz from your control for it to output 0-10v check the Power supply is connected correctly

WARNING: Check the polarity and voltage of the external power source and
connect the 12V or 15-24V, and GND. Overvoltage or reverse polarity power
applied to these terminals (X1) can cause damage to the board, and/or the power
source.

Configuring the Control Software:
It is strongly recommend you read your control software’s manual. You need to
configure your control software to control the spindle as if it was an angular axis.
This card requires a 25 KHz input signal to deliver 10VDC. So you have to set the
speed of the motor (spindle) at maximum. For acceleration values adjust them to
where you feel comfortable. Keep in mind the acceleration of the motor must also
be set in your VFD.