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false signals from clearpath enable
« on: March 11, 2020, 10:51:16 PM »
Hi everyone.  I was hoping someone might have some insight into a problem I'm having with my clearpath motors.
Here's my setup:
-C10 Breakout boards
-Clearpath Motors with HLFB+ attached to 5v pins of c10 board and HLFB- attached to various input pins.

I have the input pins assigned to limit switch inputs, and the HLFB is set to be asserted when motor is in enabled mode. Each clearpath is set to disable itself when out of position.

Normally everything works great, but every few days or so, while the machine is running, I will get an erroneous limit switch event. I know that it is not correct because the clearpath motor should show by its light display that it caused the disable, but none of the motors ever do.
I have tried adding noise filters to the inputs, but I have gone up to 60,000 us and I haven't noticed any difference in the frequency of the events.

If anyone has any thoughts about this, I'd appreciate it.  It's difficult for me to troubleshoot since it happens so infrequently and randomly.
Re: false signals from clearpath enable
« Reply #1 on: March 16, 2020, 09:04:40 AM »
Sounds like it could be electrical noise, although your filtering should have cleared that up. Do you have access to an oscilloscope? They are invaluable for capturing short and intermittent events like that.

Can you verify that your Clearpath motors and your motion controller share the same DC common potential?

Offline MN300

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Re: false signals from clearpath enable
« Reply #2 on: March 16, 2020, 10:12:32 AM »
The conventional method of using the C10 inputs for limit switches would be to set the C10 jumpers for COM = GND  and PULL-UP. Then the normally closed contacts of the switches are used to pull the inputs to ground when the switch is not activated. Is this how you wired your machine?
Re: false signals from clearpath enable
« Reply #3 on: March 16, 2020, 10:59:18 AM »
Yes, the c10 board and the ESS are both attached to the same power supply with the same ground.  I don't have an oscilloscope but I should probably get one. Any recommendations about that?  My concern is that the problem is so intermittent that I would have to sit there for days to get any information. (but maybe that concern illustrates my ignorance about oscilloscopes) :)

No, I don't have it wired this way.  I have the pins on PULL-DOWN and the clearpath connecting them to 5V when the HLFB is asserted. I think that you are on to something here. I'm going to go change that right now and see how it goes.

Thanks for all the help so far!!

Offline MN300

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Re: false signals from clearpath enable
« Reply #4 on: March 16, 2020, 11:33:53 AM »
Your message says "I will get an erroneous limit switch event.".  I would expect the limit switches to be connected to the C10 so I don't understand your mention of the Clearpath unit. Am I missing something?
Re: false signals from clearpath enable
« Reply #5 on: March 16, 2020, 02:37:49 PM »
Oh, I might not have explained that very clearly. The HLFB signals from the clearpath motors are connected to input pins on the C10, which are mapped to be limit switches.  This way when a clearpath motor goes into disable mode, it can trigger a limit event.

I think this is a pretty standard way of setting up clearpath motors, but if anyone has any objections to this I'm all ears.

I changed all of the input pins in question from "sourcing" to "sinking" like you suggested, so fingers crossed! I really hope it's not some mysterious noise issue, because tracking that down sounds out of my league.

Re: false signals from clearpath enable
« Reply #6 on: March 16, 2020, 06:42:23 PM »

This way when a clearpath motor goes into disable mode, it can trigger a limit event.

Yes, that works....but if HLFB activates is it actually a limit event? No it is a motor fault. All that you require is that the machine stops
so having HLFB trigger a 'make believe' limit works but why not use a signal better suited like ISIG_EMERGENCY?
Even using one of the general purpose inputs like ISIG_INPUT13 say with an entry in the SigLib{} table to Estop OR FeedHold or
however you wish to handle HLFB events.

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Re: false signals from clearpath enable
« Reply #7 on: March 17, 2020, 01:34:31 PM »
Ok, thanks Craig. I will get that changed around when I get a chance.  I've just never gotten around to messing with the SigLib{} table.
Is there any reason the way I have it set up to trigger the limit inputs would be causing problems? I do agree that it's not a very professional way to set it up.

I did change the inputs from sourcing to sinking, and the problem got much worse- which is good, because it's easier to experiment now and I've noticed the following:

-I am having inputs triggered by accident almost every time that I enable certain outputs and I'm not sure why this is happening. I have a relay board attached to the same 5V power supply as the ESS and C10.  It should have plenty of power to handle everything, but I ordered another larger one just in case.

-The noise filter now almost fixes the problem, but I have to crank it up to the maximum 120,000. Not a good solution, but interesting that it now has an effect, where as I don't THINK it had an effect when the inputs were setup as sourcing.

-When I measure the voltage over the pulled-up inputs on the c10, it is not up to 5V.  More like 3.5-4V. I don't know if this is something to worry about or not.

Re: false signals from clearpath enable
« Reply #8 on: May 02, 2020, 11:39:36 PM »
Ok, so I've implemented all of the suggestions and anything I could think of.  I got oversized 5V power supplies for all of the machines just in case I was getting any spikes in demand from the relay boards or anything (just a shot in the dark I know). I have all of the HLFB positive wired directly to the power supply (same power supply for breakout boards and ESS) and the HLFB negative wired to the C10 inputs. I also have the enable positives wired directly to power supply and enable negatives wired to c10 outputs.
Been testing for a few weeks now.  I already have the noise filter up to 32000 and still having intermittent false motor faults. I can't say for sure that any of the changes have really had any effect at all.

Anybody have any other ideas?? I'll consider anything at this point!!!

I am assuming that it is not anything happening because of the clearpath motors.  Whenever I get an actual motor fault i.e. one of the slides gets jammed, the motor that triggered the fault will flash yellow. When I get the random motor faults, all of the motors are solid yellow which to the best of my understanding means that the motor was disabled by Mach4 and did not intentionally trigger any fault leading up to that.
Thanks so much for everyone's help so far!!

Offline mark4

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Re: false signals from clearpath enable
« Reply #9 on: May 03, 2020, 09:51:41 AM »
Are you wires shielded? I used to use c10 boards. I use a mb3 now. On the c10 i installed capacitors .1 mf on all my inputs. Between the input and common. This did wonders in minimizing noise. The problem is the board uses 5 volts and that does not like distance. Do you have wires running next to high voltage. I learned this lesson when I ran an unshielded wire through a contractor box. Every time the contractor went off so did my estop. Switching to a 24volt board if possible would be ideal because of less noise susceptibility.