CNC Skipping G Code Instructions

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04 Aug 2020 15:02 #177251 by M Sills
I'll test that out and update if it happens again.

My current motor drivers wanted 5000 and 2500. I have noticed small hiccups while jogging so this might fix that.

If it happens again, what do I need to gather and upload?

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04 Aug 2020 17:52 #177264 by tommylight
Do you get any latency errors while running the machine ?
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04 Aug 2020 19:09 #177267 by M Sills
Nope.

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04 Aug 2020 19:24 #177269 by M Sills
How does linuxcnc send movement instructions to the 7i76e?
Does it send Gcode, steps or something else?

Is it possible I have some packet loss that causes it to occasionally miss roughly inch long commands?

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04 Aug 2020 20:05 #177274 by rodw
Linuxcnc simply tells the 7i76e to generate a step frequency until its changed..
If you lost connection, it would still generate that frequency.
But if the connection dropped, the watchdog would bite.

You can't rely on a closed loop stepper to never miss steps. If you ask too much of your steppers, they will not have the torque to catch up.

Do your drives have a fault output and is it connected to your system? If so, how is that configured?

Common sense says this is related to your configuration and hardware. If it was a 7i76e issue or a Linuxcnc interpreter issue, it would affect many people.
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04 Aug 2020 20:17 #177276 by tommylight

How does linuxcnc send movement instructions to the 7i76e?
Is it possible I have some packet loss that causes it to occasionally miss roughly inch long commands?

Chasing this route will not get you where you want to be.
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Back on topic.
Did you change the timings and test again?
And what is the acceleration set at.
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The thing that it is missing position only on rapids should be enough to confirm that you have configuration issues, not hardware or software ones.
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BTW,
Between me and my clients, we have bought over 60 Mesa cards (personally over 40), never has a single issue, ever, and i use those mostly on big industrial machines that work all day long, every day with LinuxCNC controlling them, some over 9 years of work, NEVER a single issue.

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04 Aug 2020 20:23 - 04 Aug 2020 20:47 #177277 by M Sills
I'd believe it's something wrong that I have done or something I have missed. I'm new to this so I could have done something dumb.

My steppers also have a fault detection where the error if something has gone wrong. I am in the process of hooking them up so the machine knows to stop.
Currently, it's just an LED that lights up on the stepper motors themselves.
I don't recall those being lit up when it would do something like this. I could have missed it though.
Having that communicate directly to my machine would hopefully rule it out as an issue.

Also, when changing my step generation stuff, I have developed some sort of studder in my machine. When doing linear jogs, the rpm of the motor isn't staying constant and making an odd noise.

Could this be a PID issue? I made sure that they are set to the default of 1000.
Last edit: 04 Aug 2020 20:47 by M Sills.

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04 Aug 2020 20:50 #177280 by PCW
How are the 7I76E step/dir outputs wired to the drive?

It might be an electrical issue
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04 Aug 2020 20:51 #177282 by M Sills
As for my set acceleration, would these be the lines in my .pncconf that tell me this?

<property name="xmaxacc" type="float" value="30.0"/>
<property name="zmaxacc" type="float" value="30.0"/>

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04 Aug 2020 21:04 #177287 by M Sills
For the wiring, Both my x and z are on the TB2 header.

X Axis

PUL+ Pin 3
PUL- Pin 2
DIR+ Pin 5
DIR- Pin 4

Z axis

PUL+ Pin 9
PUL- Pin 8
DIR+ Pin 11
DIR- Pin 10

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