does the PCI card connect to the router with a 15 pin cable?
I bought a used NC studio machine with a PC already set up so I didn't have to install the card or the software. I wasn't really happy with NC studio compared to mach3 on my other router so I added a parallel port breakout board.
Here's where the 15 pins went inside my router (YMMV so confirm by tracing the wires with a multimeter)
1. input for "mobile calibrator"
2. Z Step
3. Y Step
4. X Step
5. output for controlling vfd
6. Z high limit switch
7. Y low limit switch
8. X low limit switch
9. X Dir
10. Y Dir
11. Z Dir
12. output for controlling vfd
13. output for controlling vfd
15. 5V (COM on stepper drivers).
So, a basic parallel port breakout board will get you going with MACH3 although controlling the VFD can be a pain - especially if you don't have the manual. In theory - some combination of on/off on the 3 VFD outputs should get the spindle running at various speeds. I have mine hardwired to give 12,000rpm at the moment from one output (via a spindle relay on the breakout board). That's not ideal since the relay closes when the PC boots and the spindle starts - then stops when mach3 starts.
I wired the breakout board to a 15way ribbon cable with a 15pin IDC connector so I can just plug it into the 15pin socket on the router. I'll wire it in permanently when I figure out the best way to control the spindle (probably via RS485).