C6 spindle control board with Hobby CNC Pro

Hello, all.
I've been working on a Seig X2 MiniMill conversion off and on for a few years now. I've been using the Hobby CNC Pro chopper board with no issues at all running Linux CNC ver 2.5.3. Just recently purchased a C6 spindle control board from CNC4PC in hopes of gaining software spindle control. The CNC4PC information on the website regarding the Seig Spindle control board stated that the voltage should be adjusted to 7 volts. Using the Linux CNC forums, I've been able to edit the Hal & get the Axis GUI program to start & run. I just don't have any spindle control. The Hobby CNC documentation states that pins 1, 14, 16, & 17 are not pulled up & are available as needed. I have the C6 board connected to pins 14 for step & 16 for dir. When I issue the M3 command in Axis, I only get around .6 volts. I'm sure that I'm missing something here, but my brain hurts after working on this problem for over a week now. This is my 1st experience with Hal, & I've learned a lot, but apparently not quite enough. Someone please help me as I don't want to have to resort to winblows & Mach to get my little toy working. I've been using Ubuntu since Dapper, & will never go back.
Thanks

Did you set the spindle speed with the S code, Snnn before the M3?

Rick G

Thanks for your reply.
Yes, I did issue the speed command with the M3 command. I've been a CNC machinist for 36 years, so I know my way around the code. It's probably my lack of understanding HAL that is causing the problem. (Old dog...new tricks).
The HAL meter shows that pulses are being sent. It keeps changing ftom TRUE to False rapidly. It also says the spindle-cmd, spindle-at-speed, and spindle-enable are TRUE until an M5 is issued, then they all become False.
I looked at the HAL scope, & wasn't able to tell much from that. It may be an issue with the way I have it hooked up that's keeping the signals from actually reaching the C6 board..
Thanks

No, It's a 350W 110V DC motor controlled by a rheostat. The rheostat is dis-connected & the C6 board is used in it's place. I won't actually hook it up until I can adjust the voltage on the C6 to 7 volts per the instructions on the CNC4PC website. I have attached the PDF. The instructions are for the X3, but the same hookup is used for the X2.

JR

Yes, I've tried that configuration. I'm still not getting anything over .63 volts to the C6 board. I may not be using the correct ground on the HobbyCNC board I'm using the header that has the home/limit switch connections. It also has a ground connection. Pins 18-25 are used for ground according to the HobbyCNC documentation.
-JR

i'm guessing here , but i'd suspect as you do , that the ground is missing or incorrect

but to save further , post your config folder as an attached archive , and we can take a look .

The HAL & .ini are attached. Let me know if you need any of the other files. I'v made changes to the HAL since my 1st posting.
JR

O.K.

What are you using for a 12 volt power supply and how have you connected it to the board?
Does the voltage change as you change the requested spindle speed?
Have you tried adjusting the scale gain and or offset?

Rick G