Will a Mesa 7i96s work in my case?

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01 Dec 2023 16:36 #286973 by hpeyerl
I was just given a small 4 axis machine with a control box that has a proprietary control board (with parallel port) and 4x Geckodrive 201's.  I don't know the pinout of the parallel port nor do I have a computer with a parallel port.  I have lots of Linux machines though.  So to my mind, it seems like getting a 7i96s is the right answer.I'd like to confirm that the two will connect.  It looks like the Geckodrive 201's have just "STEP/DIR" inputs whereas the 7i96s wants differential STEP /- and DIR /-.   Is it enough to just use COMMON as the second half of each differential signal?  I'm a firmware guy, so this is above my paygrade. 

Appreciate the help!

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01 Dec 2023 17:03 #286976 by PCW
The 7I96S has differential outputs to support high
speed differential step/dir signaling for servo drives,
but you can use them for interfacing with single ended
drives by just using the step+/dir+ or step-/dir- signals
depending on the desired polarity.

That said, since you already have a parallel port breakout
you could use LinuxCNC with a paralle port or if that does
not provide enough performance, use say a 7I92T along
with the existing parallel port breakout board.

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01 Dec 2023 21:27 #286992 by hpeyerl
Interesting. Since I don't know the pinout of the parallel connector on this controller, I'm not sure it'll be compatible with one of the 7192T configurations; and of course, there would be a certain amount of experimentation to find the pinout. The company that made this controller ("denvercnc.com") exists only in archive.org and even then, there was no actual information on their site. The last computer that drove this thing was a WindowsXP machine that has also ceased to exist.

I'm not sure it's worth the $50 savings to go with a 7192T but this is new territory for me so I welcome the advice.

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01 Dec 2023 21:53 #286996 by PCW
Yeah, I guess it depends on whether you want to retain the
breakout that also seems to contain the power supply and
connections (plus setup switches?) for all the drives.

It would probably not be too terrible to ring out the
connections from the parallel port to the drives.

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01 Dec 2023 22:07 #286997 by hpeyerl
That's actually a good point. There are some 74ACT14's connecting to the STEP/DIR pins on the Geckodrives and the other end of at least one of the inverters appears to go to the DB25. So maybe not that hard after all.

There's an ATTINY26 in there and I assumed buzzing out the pinout was going to be a non-starter but it probably isn't implicated.

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01 Dec 2023 22:15 #286999 by PCW
Its possible the ATTINY is is used for something simple like a watchdog

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02 Dec 2023 13:31 #287020 by hpeyerl
heheh. Just a note...

I had a look at *.vhd and *.ASM and discovered D16, etc. Hat's off to you guys. Must have been a blast to do this at the time!

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02 Dec 2023 17:42 #287035 by PCW
It was fun getting this working, not so much fun trying
to understand my code from ~12 years ago when bugs
are found...
The following user(s) said Thank You: tommylight, Unlogic

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03 Dec 2023 14:47 - 03 Dec 2023 14:50 #287098 by hpeyerl
I pulled the lever and ordered a 7i96s despite your suggestion to get a 7i92 instead. My thinking is that I can always use the 7i96s on my MPCNC. Was that flawed on my part?

My friend who gave me this 4-axis machine sent me some screenshots of the MACH3 config so I now know the pins on the BOB as well as the velocity/acceleration settings for each of the axis.

I installed and started mesact and now my brain hurts. I guess I need to do a lot more reading of something.

 
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03 Dec 2023 17:31 #287107 by PCW
You could use a 7I96S 5ABOB configuration as the 5ABOB is compatible with
your breakouts pinout, the configuration would be a bit odd because the stepgens
on the 7I96S's expansion connector start at stepgens 5. (that is the stepgens on
the 7I96S remain numbered 0..4

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