First Time Help

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25 Jul 2011 18:17 #11846 by Todd Zuercher
Replied by Todd Zuercher on topic Re:First Time Help
so the post gui hal line should be some this

net Xfault-in => pyvcp.Xfault

or

net Xfault-in pcl720.0.pin-26-in => pyvcp.Xfault

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25 Jul 2011 21:15 #11852 by andypugh
Replied by andypugh on topic Re:First Time Help
Todd Zuercher wrote:

net Xfault-in => pyvcp.Xfault
or
net Xfault-in pcl720.0.pin-26-in => pyvcp.Xfault

The first would work assuming that X-fault is linked to a "write" pin in the main HAL. But would probably give you an LED with the wrong sense.
The second might give you an error, if you are assigning an output pin to an already-defined signal from the main HAL file, or will work correctly if Xfault is not defined in the main HAL.

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26 Jul 2011 01:04 #11856 by Todd Zuercher
Replied by Todd Zuercher on topic Re:First Time Help
The first one worked right.

I tried the new driver some more. I was having trouble with the amp fault. With my current configuration files I was receiving constant amp fault signals if I changed the amp fault pins to the new config (net Xfault pcl720.pin-26-in-not => axis.0.amp-fault-in), then I received an error "pcl20.pin-26-in-not not valid" and emc would not open.

Any suggestions how to track down where the problem lies?

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26 Jul 2011 02:43 #11857 by Todd Zuercher
Replied by Todd Zuercher on topic Re:First Time Help
Also when I went to backup the pcl720.ko file, I noticed that there was a file there that I had made by mistake using the long file name. How do I delete that (how do I get permission to)? On the same note is there an easy way to restore the old ko file after trying the new driver, or is it better to just rerun comp?

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26 Jul 2011 10:13 #11861 by andypugh
Replied by andypugh on topic Re:First Time Help
Todd Zuercher wrote:

new config (net Xfault pcl720.pin-26-in-not => axis.0.amp-fault-in), then I received an error "pcl20.pin-26-in-not not valid" and emc would not open.
Any suggestions how to track down where the problem lies?


if you add a line to the HAL file saying
show pin
just after the
loadrt pcl720
line then you will get a pin list that you can view using dmesg.
The comp file looks OK. One possible explanation for the missing pin is that you are accidentally using the original driver.

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26 Jul 2011 10:16 #11862 by andypugh
Replied by andypugh on topic Re:First Time Help
Todd Zuercher wrote:

Also when I went to backup the pcl720.ko file, I noticed that there was a file there that I had made by mistake using the long file name. How do I delete that (how do I get permission to)? On the same note is there an easy way to restore the old ko file after trying the new driver, or is it better to just rerun comp?


sudo rm randomname.ko should let you delete the spurious one.

As for switching back to the known-good config, perhaps the best way is to rename the new driver to pcl720new (or similar) both in the filename and the first line of the file, then one config can use the original driver, and the new config can use the new driver, and both drivers can coexist until such time as we have the bugs ironed out.

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27 Jul 2011 14:11 #11922 by Todd Zuercher
Replied by Todd Zuercher on topic Re:First Time Help
I think I figured out where the majority of my vibration problem whas coming from. It was not the servo tune afterall (at least not entirely). It was because of to great a disparity between MAX_ACCELERATION and STEPGEN_MAXACCEL. I moved them closer together and things started to smooth out. The closer I made them the smoother things got. I was then able to increase the max accel, to nearly double what I had been using, and still maintaining acceptible looking carving. I am starting to wonder if I might be able to see some advantage to adding encoder feedback. The drives are capible of passing through the encoder signal. Might this be benificial in step dir mode, and what hardware would be needed to read the encoder feed?

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27 Jul 2011 14:38 #11923 by andypugh
Replied by andypugh on topic Re:First Time Help
Todd Zuercher wrote:

I think I figured out where the majority of my vibration problem whas coming from. It was not the servo tune afterall (at least not entirely). It was because of to great a disparity between MAX_ACCELERATION and STEPGEN_MAXACCEL. I moved them closer together and things started to smooth out.

With a stepper motor system you would normally have stepgen maxaccell set to just a bit more than the axis maxaccell. I am not sure how you would tune it with a step/dir servo system like yours. I would have thought that setting the stepgen limits to zero (which I _think_ is no-limit) might be correct. You might see a further improvement with the reset option in the new driver (which doubles the max step rate)

I am starting to wonder if I might be able to see some advantage to adding encoder feedback. The drives are capible of passing through the encoder signal. Might this be benificial in step dir mode, and what hardware would be needed to read the encoder feed?

I don't think you would see any improvement, the servo loop is closed in your drives, and there is no effective way for EMC2 to use encoder feedback in what it thinks is a stepper system.
If the drives have the option of running in an analogue mode (-10v to +10v for example) then You might well see improvements in running PID in EMC2, but you would be looking at replacing the whole control PC (Or possibly using the 7i43 parallel port card, or the Pico PPMC)

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