Wiring servo drive fault outputs

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greeder88
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24 Apr 2014 18:19 #46284 by greeder88

Wiring servo drive fault outputs was created by greeder88

Where do the servo drives fault outputs go so the system can halt when a motor stalls?
My drives fault pin outputs 5v on a fault but not sure what to do with it.
5v seems too low for a solenoid in the e-stop circuit but not seeing any other choices.
My 7i77 board has enable out pins but no disable in.

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andypugh
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24 Apr 2014 19:50 #46287 by andypugh

Replied by andypugh on topic Wiring servo drive fault outputs

greeder88 wrote:
Where do the servo drives fault outputs go so the system can halt when a motor stalls?
My drives fault pin outputs 5v on a fault but not sure what to do with it.
5v seems too low for a solenoid in the e-stop circuit but not seeing any other choices.
My 7i77 board has enable out pins but no disable in.

It rather depends on the behaviour you require.

You can wire the fault input to a GPIO input pin per drive, then wire it to the axis.N.amp-fault-in pin :
www.linuxcnc.org/docs/html/man/man9/motion.9.html

Alternatively you could wire the 5V to a small normally-closed relay that breaks the E-stop loop.

Or, in fact, you could do both.

You could also consider wiring (in HAL) to iocontrol.0.emc-enable-in :
www.linuxcnc.org/docs/html/man/man1/iocontrol.1.html

Which has reminded me that I need to wire in my amp-fault inputs :-)

The following user(s) said Thank You: greeder88, thefabricator03

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Todd Zuercher
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24 Apr 2014 23:32 #46289 by Todd Zuercher

Replied by Todd Zuercher on topic Wiring servo drive fault outputs

Don't get me wrong you probably should connect the amp fault signals, but they are not nessisary in a system with encoder feedback. An amp fault will almost always coinside with a large enough following error to cause LinuxCNC to shut down anyway.

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greeder88
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25 Apr 2014 16:21 #46302 by greeder88

Replied by greeder88 on topic Wiring servo drive fault outputs

That makes sense. It's hard to visualize what can happen. A small cutter just breaks but a clogged big cutter or running the tool holder into a clamp is where the worry is. The real question is does the following error come before the amp sends the fault? If so no need to wire the fault signal. If not maybe still no need since the amp is off anyway and the following error is a millisecond away.
I guess I'm OK.

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Todd Zuercher
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25 Apr 2014 19:31 #46309 by Todd Zuercher

Replied by Todd Zuercher on topic Wiring servo drive fault outputs

I can think of one situation where the following error might not set right away. Imagine a poorly tuned drive that overloads and shuts down when no movement is commanded. Linuxcnc would not detect a following error until it commands a movement or an outside force moves the joint.

Where the amp fault in is important is on a step/dir setup without encoder feedback.

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rogerxue
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07 Feb 2020 22:17 #156716 by rogerxue

Replied by rogerxue on topic Wiring servo drive fault outputs

question related to the topic:

my servo only power up when linuxcnc powers on, so there's a delay between the power on and the signal from servo alarm turns off.

if I wire the servo alarm to amp-fault, it will trigger immediately after machine powers on, due to the delay. any suggestions what I should do?

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Todd Zuercher
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08 Feb 2020 04:45 #156741 by Todd Zuercher

Replied by Todd Zuercher on topic Wiring servo drive fault outputs

I would use a combination of a timedelay hal component connected to the amp enable output, then the output of that to an and2 comp combined with the fault input from the drive, then the output of the and2 to motion.axis.N.amp-fault-in. This would essentially disable the amp's fault signal until the timdelay expires after turning on.

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rogerxue
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08 Feb 2020 13:44 #156760 by rogerxue

Replied by rogerxue on topic Wiring servo drive fault outputs

that makes sense, thanks

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