Mesa SoftDMC homing question

16 Feb 2017 12:32 - 16 Feb 2017 12:48 #88046 by superlen

I've been looking at the Mesa cards for my gantry build, but also think they might be a good solution for another machine (non cnc - more robot like) I would like to write some software for. It has 8 axis (all steppers) so I was planning on a 7I92 Ethernet Anything I/O card with two 7I47 Stepper daughter cards.

Can you configure SoftDMC to know the inputs for your home and end travel sensors & then SoftDMC can home an axis with an ethernet command? My assumption is that this can be done, but is it a default type of operation with just some simple FPGA configuration, or is it more of a R&D effort? In LinuxCNC, does the Mesa interface handle homing & over travel, or does the pc side software handle that?

My desire is to configure the 7I92 to act as a simple position controller & I feed it just a few commands over the ethernet, namely Home and Axis Position. If I tell it to move too far, it would of course stop at end point and report back warning/error ect.


Last Edit: 16 Feb 2017 12:48 by superlen. Reason: typo daughter card number
16 Feb 2017 21:42 #88079 by tommylight
If i understood you correctly:
Mesa 7i92 does not do homing and limits, Linuxcnc does that when and if it gets the signals from 7i92 or any other mesa card.
You can send data all the time at a rate of 1 KHz to and from 7i92, that is smart serial data so PCW can explain it better at what exactly that means.
No need for softDMC, everything you want can be easily done.
Some older Dell optiplex computers are quite good for Linuxcnc. And some workstations from Dell or HP or Fujitsu Siemens.
16 Feb 2017 21:56 #88083 by superlen

Thanks for the info. I should have specified on this project I wouldn't be using linuxcnc, but rather my own code. I was trying mostly to determine if my code needed to read limit switch inputs and handle homing and such, or would softdmc do a lot of that under the hood.

Ideally, I just send a packet over the link to have softdmc move to location x, and it happens within the bounds of my home/end travel sensors. If I need to also handle the sensors in my code, that's fine, but given the option, I would rather softdmc handle it. I would think at the least, soft dmc must handle some of these inputs for safety concerns. If the link goes down, SDMC im sure stops motion. It follows that you could tell it to stop on an input going hi as well.

I may be over thinking this.

17 Feb 2017 23:29 - 17 Feb 2017 23:31 #88141 by BigJohnT
The 7i47 is a 50 pin card and the 7i92 is a DB25/IDC 26 card... they don't mix. The 7i78 will work with the ]7i92M .

Last Edit: 17 Feb 2017 23:31 by BigJohnT.
17 Feb 2017 23:31 #88142 by PCW
You can use a 7I47 with a 7I93 however
02 Mar 2017 02:55 #88858 by superlen
7i93 (50pin) was what I had in my head with a 7i47 behind it. I just placed an order for those 2 and the Servo 7i33TA interface. These three should let me play around with some of my hardware.

Thanks for the feedback.

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