Is there a limit as to how many parallel port cards can be used with Mach3??

 I am currently running 2 in the machine I am building. the first card is pretty much used up controlling the TB6550 controller board. it seems to require Step, Dir & enable pins for all 3 axis plus spindle control and there are no pins left.

 I added a second card to control some Solid state relays for Vacuum and flood pump and I am using the rest of the pins for manual direction control.

 But I would like to add a 3rd card so I can utilize the P.I.D function for spindle speed control. I just don't have anymore available inputs on the 2 existing cards.

 So I'm curious if I can run 3 cards with Mach3. assuming I can get 3 cards to run in the PC in the first place.

Two parallel ports is the max as far as I am aware.
Hood

that's a bummer with only 10 input pins. I need one more! or i need to re-think how to do the jog buttons.

I currently have:
X Limit
Y Limit
Z Limit
E stop
Jog X+
Jog X-
Jog Y+
Jog Y-
Jog Z+
Jog Z-

 and that wipes out all 10 pins. I need a way to get a speed pulse into Mach3 any suggestions??

 I suppose I could disassemble a USB keyboard, remove the keyboard PCB and wire the arrow keys to the direction buttons on the panel. that would free up 6 input pins. but i really don't want to do that if i don't have to.

 Plus I would like to be able to add a digitizer at some point and that will require yet more pins....hmmm

you could wire the x, y, and z limit switches in series and run them into one input, which will give you two inputs free.

I was wondering if i could do that or if there was a reason it needed all 3?? sweet well there are the 2 pins i need then!

Other thing to look at is something like the PoKeys, it will give you approx 55 I/O if I remember right. Time critical things such as home switches and step/dir will need to be on the port but things like external switches the Pokeys will handle very well.
Hood

You can probably use a jumper to enable your drives, and not have to use the paralel port, which free up 3 pins. Are you using a breakout board that allows pins 2-9 as inputs on the second port? That may help.

I have 2x 25 pin breakout boards in my custom motor controller box. I have access to all 25 pins on the BOB, there is a cable that connects from the BOB to the circuit board. so yes I have access to all pins. So can i jumper the enable lines to +5v? or should I jumper the three axis together to one PC port enable pin?

 I am using a HY-TB4DV-M Toshiba TB6560 motor controller board commonly found on eBay.

If its any help I have taken all enable lines through toggle switches (mounted on the controller case) to +5 volts  and this allows an axis to be disconnected if required for any purpose.

Tweakie.

sweet. ok I am reworking how I am going to do this then. Thanks!