Problems with 7i76e setup

I believe I found the thread with the wiring diagram attached by rodw:
forum.linuxcnc.org/27-driver-boards/3191...76e-connection-sheet

One reason I was looking for some discussion regarding this was that I fear there is a problem with the following:

rodw wrote: I have deviated from this setup which seems the same as yours becasue I have applied 5 volt power to P5. That means W1 jumper needs to be changed. Just note that if you use the MPG encoder inputs, you need to tie the GNDs together as per the note on Page 2.

I do agree that you need to connect the GND:s together with the wiring as presented (perhaps the MPG could be fed by +24V, though, which would allow to keep logic and field power separated). But I do not think that the jumper W1 should be changed. It seems to me that if you do that and supply +24V _only_ to pin 5 on TB1, the field I/O ports would be left without power. However, if you have VIN and VFIELD connected through external wiring, that would then allow it to work. I could of course also be mistaken By the way, I do believe you mean P3 instead of P5 (i.e. a typo).

deawe wrote: rodw, thanks for the wiring diagram, that is very helpful! I have been looking for something similar, but my searches turned up empty. Do you happen to remember in which thread this was posted? It would be interesting to see a little bit more about it.

Thanks to you all for the prompt and valuable support!

No worries, I'm glad you found the source. I couldn't. even after I posted some revisions that were incorporated into it. If I could have found the thread, I would have posted a link to it instead of attaching my copy of the document. Sorry, yes, the diagram was hard to read on my tablet. P3 it is. MPEG inputs are 5 volts as that is what the devices require.

In my config, all of the Field power pins (TB1-1 to TB1-4) are tied to +24 volt based on some photos published somewhere. From memory, this allows greater current handling on the I/O pins.

I bring up this old thread only to inform you about the conclusions, or rather the current situation.

When making a claim to EUsurplus, they told me it's better to deal directly with Mesa, which I did. I sent in the card for investigation/repair, and Mesa informed that there were signs of over or reverse voltage, but accepted to replace the card anyway. I am quite confident that I have not supplied over or reverse power to the card and that the card was in that condition when I got it. But of course it's difficult to be 100% sure.

In any case, I got the new 7i76e card from Mesa, and hooked it up tonight. This time I took precautions and hooked up a digital storage oscilloscope to measure and see the transient power-on voltage. Nothing strange there, and the card appears to be working without problems. I have yet to hook it up to the stepper drivers, but now the DIR output is changing polarity as expected, and the field outputs work.

Below a photo of the current setup, in case somebody is interested. Still quite a lot to do before the electrical side is completed.


And a last thanks to all the support you and Mesa gave! It's not a long way to go anymore to a working CNC mill

Side note, do not use that flat cable for communication, i have one, it does a lot of droped packets. Use UTP or even beter STP CAT 6 cable.
UTP = unshielded twisted pair
STP = shielded twisted pair
Key word there : twisted pair
Flat cable = no twisted anything and most probably no shielding.
Yours might just be good good, mine is not by any stretch although it looks niceeeee.

You, sir, have a keen eye! As you are suggesting, I do not intend to use that ethernet cable in the final setup. Right now, when doing most of the wiring and testing, this was what I found with a somewhat suitable length.

In any case, thanks for pointing that out!