Data Logging With Linuxcnc?

Greetings, I’ve been lurking/reading up for a few weeks now & was unable to find much via search regarding data logging with Linuxcnc.

To give a bit of background, I’m troubleshooting an older large (12’) gantry router/table that is fitted with a motor & drive on each side of the machine & currently it seems that the two sides are fighting each other. I have a pair of 500ppr incremental rotary encoders that I was hoping to fit one to each side & log this data as well as a few other analog signals (drive amperage draw), & hopefully plot out where the error(s) are occurring. Is this something that would be possible within Linuxcnc?

Obviously, a lot of this is outside my current comfort zone, but I’m eager & willing to learn!

Thanks!
Eric

Halo Eric,

may be logging positions may be apossibility.

How to log is explained here:

www.linuxcnc.org/docs/2.4/html/gcode_mai...ml#sub:Probe-Logging
Norbert

Hi

I personally would favour a user-space component.

The immediate problem with logging via gcode is that it only does it when the line is reached.
So the move before would be executed and then the log entry would be made. This is fine for probing, because you only want the co-ordinates or whatever when the probe triggers.
I suspect you want to be able to see what each motor / axis is doing and compare the two throughout the duration of a move.

The principle is quite simple, you create IN pins in the component which are netted to signals that hold the data you want and the component writes the data to file at pre-determined intervals

This is for digital data, TRUE / FALSE, value of float etc.
It is not so simple to get analogue values such as current drain, because these would have to be introduced some how into the data available in HAL.
It quite honestly might be easier, to put an ampmeter onto each motor power line and compare the readings during a preset run, if you are suspecting a motor problem or some sort of binding requiring higher power to achieve the same movement etc.

The main thing you need to decide is specifically what data you need to record, what form it is in ( digital signal on / off, float value, signed int etc) and the appropriate signal which holds it.

I am sure we can come up with something that will write it to file

regards

andypugh wrote:

EW57 wrote:

I was hoping to fit one to each side & log this data as well as a few other analog signals (drive amperage draw), & hopefully plot out where the error(s) are occurring. Is this something that would be possible within Linuxcnc?

Yes. You might find you can do what you want with Halscope, otherwise look at halsampler and streamer.
www.linuxcnc.org/docs/html/man/man1/halsampler.1.html
www.linuxcnc.org/docs/html/man/man9/streamer.9.html

Yes, I think the kind of data you want could EASILY be taken with Halscope. With the servo
thread at 1 KHz, you can get a 4 second buffer. There is also a little bit of math capability
in Halscope, but you might need to do some simple math (scaling and offsets of the
two encoder values, perhaps) with some HAL components to get the exact data you
want to display. But, maybe starting both encoders off at zero, then you
could display the difference between the encoders as you make jog moves.

LinuxCNC doesn't have a wide variety of analog input features, but I think there
are some Mesa boards that can do it.

Jon

Thanks everyone for your input! I'm glad to hear this sounds like a workable possibility, obviously I've got a fair amount of reading & learning before I can actively pursue this project. Thanks again!