Mesa 7I76 with Spindle encoder and MPG-need help

I am retrofitting a Bridgeport Boss5 machine and have purchased a Mesa 5i25 and 7i76 daughter card for it. I see how to configure the spindle encoder but an unsure of how to add the MPG encoder to the config and what IO pins to connect it to. I was planning to run the field power for the limit switches at 24 volts, this will work for the mpg axis and step size selection switches but what about a 5 volt ttl encoder?

The 7I76 MPG inputs will work with 5V signals (they have a 2.5V threshold)

If you have a single MPG, its A and B lines would connect to field inputs 16 and 17

So if I understand this right, the logic high level is 2.5 volts even when using field io powered at 8-32 volts?

eman5oh wrote: So if I understand this right, the logic high level is 2.5 volts even when using field io powered at 8-32 volts?

On the MPG inputs only, in MPG mode, yes.

slowly slogging my way through a retrofit on my Boss, after sorting a motor issue I am back to wiring things up. Is the 5 volt ground connected to the field io ground? Can it be? The pendant I use is wired up to a db 25 connector and the switch commons and encoder 0volt are shared.

Field I/O ground is isolated from 5V ground.
They can be commoned if desired

I plan to use mode 2 for the 7i76 and set the mpg encoder up on 16 and 17, the encoder is a 5 volt encoder. How do I set this up in Linux cnc? The rest of the io on the pendant can be run at the field io voltage of 24 volts I just need to seperate it, can I keep it isolated from the 5 volt ground in mode two?

In MPG mode the threshold of the pins is set to suit 5V input rather than the threshold of the other field IO.
To use the 5V supply you will have to common field-io gnd and 5V gnd.

If you prefer not to do that then you could use a buck converter to make a 5V from the field IO supply just for the MPG.
They are extremely inexpensive: www.ebay.co.uk/itm262248404873 as a random example.
There are others with an LED display of voltage, but they cost twice as much.

I picked up a buck converter and have the MPG encoder wired to TB5 16 and 17. The rest of the pendant IO is also wired to TB5 as follows axis select x 18, y 19, z 20, A 21, 1x step 22, 10x 23, 100x 24, and estop to 25. The io other than the encoder are set to use the field power at 24 volts. I looked through the config tabs in pncconf and it was not apparent to me how to configure anything other than the estop. Can someone point me to a guide or post on how to set this up with the 7i76? Thanks

I have made a little more progress, I found were to set the serial to mode 2 and I now have the encoder options for for pins 16,17,18 and 19. I am not seeing how to set the axis select or the step size though.