Mesa 7i97 analog out issue

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27 Jun 2022 22:31 - 28 Jun 2022 03:02 #246028 by pmaskale
Background:
I am working through my first LinuxCNC project. I’m an electronics engineer and am relatively versed in servo systems, feedback devices and control loops. Though I am stuck, I have to say that I love the idea of this controller and will probably love it even more once it cuts metal. Already planning a future lathe retrofit.

I am currently retrofitting an old but free 1985 Bridgeport R2E4. Luckily all of the old controls were repairable and after a bit of troubleshooting and replacing a component or two I was able to successfully test out the system with it’s old controls. The old velocity controls have now been severed form the drives and all of the critical things interfaced to my 7i97. So far I have drive enable, home switches, and all 3 axes of encoder feedback wired up, scaled, and reading properly from AXIS via LinuxCNC 2.8.2. I’m using a pretty basic ini and hal config that was generated with pncconf for an older Mesa Card (since the 7i97 is currently not supported in pncconf)

Problem:
I am stuck at the analog out. I seem to get nothing from the analog outs. I’m testing solely with the Y axis now as I have the servo assembly removed from the motion stage.  When I enable the drive my servo drifts slightly with the growing position delta displaying on AXIS. When enabled, I expected the system to counteract the servo drift and stop(workie), go unstable(too much P), or runaway (sign reversed). Instead, nothing happens. I get zero analog out (verified with o-scope). I increased the following error parameter giving me time to jog the Y both ways with no change in output voltage.

I successfully tested the 7i97 directly from the HAL CMD line. Enable the output channels and send a value from 0-1 to get the -10 to 10v out. Because this works, I assume it is something in my hal, ini, or my understanding of LinuxCNC.

When I get home in a few hours, I will post up my .ini and .hal files. Is there anything else that would be useful to troubleshoot and/or include with the ini and hal. Thanks for any assistance. I usually like to dig in and figure these things out, I just don’t have time and would really like to move on to servo tuning and CAM programming.
Last edit: 28 Jun 2022 03:02 by pmaskale.

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28 Jun 2022 00:00 - 28 Jun 2022 00:00 #246036 by JPL
Replied by JPL on topic Mesa 7i97 analog out issue
I'm really doesn't have enough expertise to be able to help but I can assure you that the first thing the Wizards living here will ask is to see your ini and hal files so they can investigate...
Last edit: 28 Jun 2022 00:00 by JPL.

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28 Jun 2022 01:05 #246041 by pmaskale
Replied by pmaskale on topic Mesa 7i97 analog out issue
Here are the hal and ini 

After the kids get to bed I'm going to try to learn how to use the HAL Scope and start probing around.

Thanks
Attachments:

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28 Jun 2022 18:16 #246093 by pmaskale
Replied by pmaskale on topic Mesa 7i97 analog out issue
In the INI file I have MAX_OUTPUT=0.0. This seems like it should be around 10. I remember setting it to 10 and still seeing zero output. Maybe I had another issue at the time as well.

Are the JOG commands filtered through this limit too?

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28 Jun 2022 18:54 #246094 by tommylight
You said you are testing the Y axis, and for it the max output is set at 10.
Have a read through this,
forum.linuxcnc.org/10-advanced-configura...ning-detailed-how-to

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29 Jun 2022 11:45 - 29 Jun 2022 11:52 #246150 by JT
Replied by JT on topic Mesa 7i97 analog out issue
You might want to try my Mesa Configuration Tool .

JT
Last edit: 29 Jun 2022 11:52 by JT.

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29 Jun 2022 22:49 #246229 by andypugh
Replied by andypugh on topic Mesa 7i97 analog out issue
I think you are missing a PWM enable.
net y-output     => [HMOT](CARD0).pwmgen.01.value
net y-pos-cmd    <= joint.1.motor-pos-cmd
net y-enable     <= joint.1.amp-enable-out

Append
net y-enable [HMOT](CARD0).pwmgen.01.enable

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30 Jun 2022 04:38 - 30 Jun 2022 04:40 #246249 by pmaskale
Replied by pmaskale on topic Mesa 7i97 analog out issue
[SOLVED] Thanks everyone for reading through this and helping out.

Andy you called it. Unfortunately I didn't see your post until I stubbled across the same thing. Was poking around in the Hal Configuration window a bit this afternoon while going through Tommy's analog setup tutorial.

I noticed that the [HMOT](CARD0).pwmgen.00.enable (X axis) indicator was changing state when I enabled the drives but the net y-enable [HMOT](CARD0).pwmgen.01.enable (Y axis) was not.

The Y drive was physically being enabled from the Y enable pins because the mesa card runs the first 4 axes enables off the X enable signal. However the [HMOT](CARD0).pwmgen.01.enable needs to be active for the analog output to work. Unfortunately x was still in the default INI configuration with MAX_OUTPUT set to zero, otherwise I would have likely seen analog out working for X and got to this conclusion sooner.

I know this is likely obvious to most of you guys, I'm just being verbose incase someone with the same problem finds this thread.
Last edit: 30 Jun 2022 04:40 by pmaskale.

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30 Jun 2022 08:52 #246257 by tommylight
I missed it! :(
I blame glasess! :)

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