I have a USB SS. I have been using it for several years. I have a BOB that only is setup for 1 port. I have run out of inputs, and would like to add six more.

So, I find that the SS has a header called Port 3, which (from everything I have read) appears to let these port 3 pins be used as inputs...great right? well, if I can figure out how to configure that in SS config and Mach 3, It would be excellent.

I have the port 3 in the SS config. They are checked, and set to 5V input. This appears correct.
I have gone into mach 3 setup/ports/pins and tried setting an an X limit to port 3 pin 1. I then hooked up a switch to the +5V on the SS. It appears I may not have more than 1.1VDC on the 5V pin.

I also tried using an external (not from the SS) 5VDC for the input voltage for port 3 pin 1. This gave me 5VDC when applied, but when not applied, I still had 4VDC on port 3 pin 1. Odd, because when I ran the same 5VDC through the switch (that I am using for testing) i got a clean 5vdc and 0vdc. depending upon wether the switch was activated or not (as it should be)

I dont get how I would configure Mach3 ports/pins/inputs to use SS port 3 pins 1-6?

Additionally- the mach 3 inputs page appears to only allow me to use pins 10-13 and 15 as inputs. I assume that if I have port 2 enabled in port setup/axis selection I should be able to use pins 2-9 as inputs...however the imputs page seems to say this is not allowed, as onlt 10-13 and 15 can be used as inputs...

So...does mach 3 really only let me use ports 1 & 2 and on each I can only have 5 inputs (pins 10-13 and 15)??

I am using mach 3 version 3.043.022
And SS
plugin beta2 0.015ogx
FpGA 37
driver version 2.08.36  

I also  

I am thinking about removing the BOB, due to it being only 1 port.

I could then attach to my USB SS the CNC4pc C25 board to have full pin access to ports 1 and 2.

I will loose opto isolation though... I could nto find a board that just does opto isolation, although, I thought for sure that one would exist.

Connect port 3 pin 1 to gnd via your switch and it should work.
Regarding port 2 you can choose in the SS plugin to have pins 2-9 as inputs so you would have 2-13 and 15 as inputs and 1, 14,16 and 17 as outputs.
Hood

Interesting... are the SS port 3 pins already "hot" by default?

Would I put in port 3 pin 1 into mach3's ports and pins tab (for the feature I select, say...X+Limit) ? 

Yes port 3 pin 1 is what you would put in.
Hood

Thanks Hood!

Last night I stripped down my controller so I could rewire and get rid of the bob and just use the C25 breakout board. This will give me both SS ports 1&2.

When I put things back together, I will retest the 3rd port pins and see if I can get them to work.