Using a 7i92t as replacement for a parallel port

Thanks PCW. Yes, I guess I'm not understanding the configuration software. As shown in your second screenshot, pin 002 (which corresponds to pin 2 in the DB25 connector) shows "XAxisStepGen" and beside it, grayed out "Step Gen-A". Pin 004 (which corresponds to pin 3 in the DB25 connector) shows "XAxisStepGen" and beside it grayed out "DirGen B". So, I said to myself: "Step is being output in pin 2 and direction in pin 3." I need to swap them somewhere. Is my logic flawed? 

Sorry for the insistence, I want to understand the configuration tool.

 

Those are G540 pin assignments (which can be ignored)
The only important thing with the stepgens is that you assign:

0 --> X
1 --> Z

( and whatever inversions you need, note that these inversions
apply to the stepgen, not the indicated pin so will be correct
even though "wrong" firmware was chosen )

Edit: I forgot to add that you can use the "discover" option to get the
correct pin numbers in pncconf, this requires that you setup the host
network so you can communicate with the 7I92, install the correct
firmware, power cycle the card, and then run the discover option in pncconf.
 

Motion in both axes and estop are working!! The spindle is not, but I guess that's easy to solve. And so far no smoke is coming out of any electronic component!!

Thank you unknown and PCW for your help. Now it's just a matter of adjusting parameters, the X axis is too slow, the Z axis looks right. I also want to configure the vistacnc pendant, but that'll be another topic if I don't manage.

Thanks again.

As a recap and for reference:

0. Yes, the 7i92t can replace a parallel port, with the advantages of more functionality, more reliability and that it offloads critical processing from the computer's CPU. One caveat for my particular use case: the card needs an external stable 5V supply. 

1. In my case, I was connecting a lathe that has a DB25 connector and I needed the following signals: ESTOP (pin 1), XDIR (pin 2), XSTEP (pin 3, inverted), ZDIR (pin 4), ZSTEP (pin 5, inverted) and SPINDLE ON/OFF (pin 16). The following is the correspondence between the DB25 pins and IO Pins in the Mesa card:

DB25 => 7i92t
01   => IO Pin 000 
02   => IO Pin 002 
03   => IO Pin 004 
04   => IO Pin 006 
05   => IO Pin 008 
16   => IO Pin 005 

IMPORTANT: in computer parallel ports, pins 18 to 25 are GND pins. Jumpers W1 and W2 on the card must be set as pull-downs to GND by putting them in the down position. 

2. A firmware needs to be selected that matches the requirements. For that, you need to download the support files for the card from mesa. I got mine from: www.mesanet.com/software/parallel/7i92t.zip. After unzipping the file, navigate to the hostmot2 directory. After inspecting the format of the .pin files, I used the grep utility to find the files that matched the step generator pinout I needed, like this:

grep -il " 3.*4.*stepgen.*step" $(grep -il " 2.*2.*stepgen.*dir" *pin)

That grep is not perfect, I checked the 3 files manually and the firmware that was the best fit for my pinout was the 7i92t_benezanx2d.bin (the one that corresponds to the .pin file)

I uploaded the firmware to the board using the mesaflash utility.

3. I ran the pncconf utility and created a new configuration. For the card discovery utility to be available, "Show Advanced Option Pages" in the "Start" page needs to be enabled. That utility reads the pinout from the firmware when you get to the "Mesa Card 0" page.

The machine is running well, I made mistakes like disabling the "Include spindle" setting on the "Base Information" page, that's why the spindle was not turning. For the motor setup I only needed to change the scale, which was simply the number of steps per mm. I also changed maximum speed and acceleration, and the hold times according to the configuration I had from when I used the parallel port.
 

Thanks for elaborating, a lot of those that visit very rarely document their experience. This is very useful and many thanks for your time .