Mesa 7i96 system planning-How Supported is Supported?

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03 Apr 2018 11:40 #108294 by Xnke
After reading a few other threads here on the 7i96, I am unclear on what is and is not supported with this card-it seems to be *the* bargain card out of all the Mesa hardware cards listed as "Linuxcnc Compatible" on the Mesanet website.

After reading the 7i96's specifications, this is what I had in mind when I chose to work with this card:

5 step/dir outputs-> I plan to run XYZ axes, plus a "sometimes used" rotary 4th axis for dividing head/splining.
1 High speed encoder interface-> Spindle encoder, quadrature but still need to work out a "home" input
11 isolated input-> Limit switches on XYZ axes, E-stop input, spindle coolant interlock, touchplate for tool height, spindle "home" input, enclosure not closed, etc.
6 isolated output-> Coolant on/off, E-stop activated (light up a light) tool changed requested (light up a light), program active (light up a light)
RS422/485 interface-> Spindle control via RS485 to the VFD, on/off/speed

Can anyone here update us all on what of the above list is supported, and to what level it is currently "working"? I don't mind working out new hardware...but I am not good enough with coding to re-write an unfamiliar firmware. Last one I did was a year-long effort at General Motor's version of Motorola 68HC11 Assembly...I still have nightmares...

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03 Apr 2018 14:18 #108308 by PCW
The 7I96 is supported by LinuxCNC master, though there is no current way to do Modbus
for VFD control via the RS-422/485 port

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04 Apr 2018 02:05 #108345 by Xnke
After talking to the gentleman at Mesa today, I think I can bash together some existing HAL and modbus stuff to get RS485 working with this card. I'll know fairly soon, as I am moving along with the construction of the frame, it'll be time to order the first batch of parts this month.

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06 Apr 2018 12:12 #108491 by andypugh

there is no current way to do Modbus
for VFD control via the RS-422/485 port


I wonder how hard that would be?

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06 Apr 2018 12:47 #108497 by PCW
I dont think its _too_ hard, maybe just grafting the hal/modbus part of mb2hal or one of the
specific VFD drivers to a different lower level serial driver.
Unfortunately the existing packet UART driver is pretty awkward to use.
I think If i did it I would make a real time driver that polls the UART at the servo thread rate
(1 ms granularity should be OK for Modbus)
I'm willing to help with any needed firmware mods

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06 Apr 2018 13:00 #108502 by Todd Zuercher
I certainly would be interested in such a feature if someone ever figures it out.

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09 Oct 2018 02:06 #118572 by Xnke
So, I have waited for a while to see if support for the 7i96 would improve, and it seems it has somewhat. I have changed jobs and now work in a CNC job shop, so this project can move forward a bit at a time now.

It seems that we still don't have support for using the RS-232 port for anything outside of other Mesa cards, but I don't think anyone else has looked for it yet either.

this is going to make me ill...buying a bunch of spendy parts without a clear-cut plan. But, it's the way it goes, I'll make it work.

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09 Oct 2018 10:37 #118581 by andypugh
Using the RS482 port for something else is just a case of flashing a different firmware.
I used a custom firmware for a while which put a UART on one channel.
In fact it made it in to the firmwares repository:
github.com/LinuxCNC/hostmot2-firmware/bl...src/PIN_Andy1_72.vhd
It's not likely to be useful to you, but does demonstrate that you can add a UART.
(In this case I was using an Arduino to read resolver positiona and send them over serial, but it never really worked properly and I switched so a 7i49)
The following user(s) said Thank You: silopolis

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10 Oct 2018 18:05 #118645 by Xnke
So the 7i96 now has a firmware UART that can speak standard RS485, which means we may be able to send modbus commands over it...this is exactly what I had been waiting for.

Too bad I didn't go ahead and buy the spindle and VFD that needed Modbus, back when I could obtain them inexpensively. Now I've got a 1200W DC permanant magnet motor that I need to build a controller for, I figured it would be easiest to simulate a X3-ish style controller, since many people have those working.

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11 Oct 2018 20:07 #118685 by andypugh
We don't currently have a Modbus driver for the Mesa UART. But one would be a very welcome addition.

It would need to look a bit like this

(Which, as you can see, other than pin definitions and documentation is just 3 simple functions)

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