Which Mesa combination should I choose?

Looks like the 7i76 is the preferred choice for future expansion. The 7i96 would cover my current needs. If I look back at the evolution of my machine over the years it is clear future change is inevitable!

I found Norbert's connection guide which will be a great help. Thanks for all the current and likely future help.

John

cncbeagle wrote: Looks like the 7i76 is the preferred choice for future expansion. The 7i96 would cover my current needs. If I look back at the evolution of my machine over the years it is clear future change is inevitable!

I found Norbert's connection guide which will be a great help. Thanks for all the current and likely future help.

John

Sounds like a good choice. I think I have used just about all of the 7i76e's 32 inputs! And most of the outputs!

One mistake I did was to use the analog inputs early in the piece for digital inputs. Nrbert sets it straight but he released that after I wired everything up so I have never gone back to it.

Following up on the original question.

I did purchase a 7i76e and now have it hooked up and operating. I now have spindle start/stop and speed control. My spindle is a Porter Cable router fed through a KBIC-125 speed controller.

There may still be some optimization opportunities. In testing the gantry steppers before mechanically connecting them I noticed one was limited to a lower speed than the others. I have ordered two new higher torque, lower impedance steppers. The gantry speed has been what limits my cutting speed. I'll see if the more powerful motors help or if one of the Longs Motors DM542A drivers is the culprit.

I am able to drive my X axis much faster with the Mesa board than with the parallel port. It has a larger motor and DM556 driver. I have tested it up to about 15KHz but limit it to about 10KHz in operation as that is still faster than the Y gantry. With the parallel port it operated at about 8KHz. It might have been able to go a little faster but never at 15KHz.

The change to Mesa was driven by a PC software and hardware upgrade. Any performance gain is a bonus. I was able to simplify some wiring and now my CNC machine is all on a single table that I can move around my shop as needed. The PC gets as much use as a general purpose computer as it does running LinuxCNC.

For me this has been a worthwhile upgrade. Thanks to many on this forum it was relatively easy if a bit time consuming.

Another follow up in case someone finds this thread useful...

I finally received the new stepper motors for my Y gantry. The new motors are higher torque and lower inductance. With these motors I have more than doubled the speed of my Y axis. I am hesitant to push even further but probably could. I suspect these speeds would have been beyond the reliable limit of my former parallel port setup.

Just another reason to be satisfied with the Mesa upgrade.

Also I'm looking at connecting outputs to control an air "blast" and vacuum. Having all this unused I/O is giving me lots of ideas!