The pins on the SS are like the parallel port, in other words on Port 1 you have 1 to 9, 14, 16 and 17 are outputs and 10-13 and 15 are Inputs. Port2 can be either the same as port 1 or you can configure it so that Pin 2-9 are Inputs rather than outputs but all other pins remain the same. Port 3 has 5 inputs 3 of which are differential so can be used for encoder/MPG inputs if your encoder MPG is differential.
As for which Input or Output does what, well that is up to you and you just configure that in Mach, for example if you have limit switches connected to Port 1 Pin 10 you just assign that in Machs Ports and Pins, Inputs page.

Hood

Can you walk me through that a bit more?

Currently I have a running 3 axis CNC.  I'm running XP, Mach3 to my Smooth Stepper, to a G540.  On my machine my Y uses two steppers so I use Y & A from the G540.  I'd like to add a 4th axis.  I purchased a 2nd DB25 cable for port 2, a C10 BOB and G251X driver.  I have a basic idea of how things work, but can't figure out how to tell Mach3 which output (in the ports and pins section) the 4th axis (B) stepper will be.  Gecko provides a doc for the G540 so I never learned how to do this.

Hood, I understand what you're saying about the layout of the pins being like a parallel port.  But, my 4th axis uses port 2.  I see that I need to tell Mach3 port 2 is up (the check box), but what will the pins be?

Thanks in advance,
CNC Dan

The pins will be whatever you have the drive connected to, afraid I cant say more than that as I have not wired it
Hood

CNC Dan;
Does your driver board have 4 outputs?? if your using Y and A outputs then you might not have enough driver/stepper outputs. Worse case hook it up like you think it should be and put a volt meter across the 4th axis output run 2 or 3 g code statements and see if the voltage on the output changes
good luck

You would connect pins 2 (step) and 3 (dir) of port 2 to the G251 step and dir pins  just like it's done with the other 4 drives on port 1. Then in Mach3: config->ports and pins, enable the B axis and set pin2 port 2 for the step and pin3 port 2 for dir. You will have to look in the manual for the G251 pinouts for step,dir, ect.. As far as I know both the SS and Mach3 are supposed to be capable of driving up to 6 axis.

TJ


EDIT: I missed the part where you were using port2 for the A axis. You can put it pretty much anywhere on pins 2 thru 9 on either port, it's how you set it in config that counts. It could even be b=pins 2 & 8. I think most people use the 2/3=x 4/5=y, 6/7=z convention cause it's easy to think about it that way.

Hey folks,
Sorry for the delayed response, life always gets in the way.  Attached is my current ports and pins layout.  And, here's a link to my C10 BOB manual http://cnc4pc.com/Tech_Docs/C10R10_USER_MANUAL_V2.pdf

I do understand the C10 connections (2, Com, 3) to the G251X (9, 10, 12).  At least I think I do.  The thing I don't understand is what do I tell Mach3 to get it to turn the 4th.  As you can see on the ports and pins layout, numbers 2-9 are all taken.  Do I go to 10 & 11?  Also I made a mistake earlier, I meant that I wanted to put the 4th on the "A" axis, my Y is now my Y & B.  Oh, and disregard the spindle settings; they are not used.

Thanks,
CNC Dan

You would tell Mach which pins on Port 2 you have it physically connected to so it may be 3 and 4 , the difference is you will say its port  2 . You already are using pin 2 on port 2 for the spindle so you cant use that.
Hood