Mach 3 or Kflop buffering commands?


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Thread: Mach 3 or Kflop buffering commands?

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    Default Mach 3 or Kflop buffering commands?

    Hi Tom,

    We have an issue which I am not sure if it is Pendant, Mach 3 or Kmotion related but maybe you can give us your thoughts?

    Using the P2-SE Pendant (usb) connected to Mach 3 and then to a Kflop/Kanalog motion system driving servo motors. I experienced an issue last week where the pendant stopped responding (using the pendant) so I triggered the estop in Mach then reset it and on reset the system immediately moved in response to the last commands I entered via the pendant for example Jog Z down. I hit reset to stop the motion and it did stop but as soon as I reset the estop it moved again still executing the commands entered from the pendant when it first failed.

    I hit estop and reset a few times but it kept trying to move, estop usually kills all existing commands it was like something had buffered commands it was trying to send is this possible?

    I cleared it by power cycling the whole system. This is an issue as it’s not safe and broke a tool and damaged a height gauge.

    Now it could be buffered somewhere else but I thought I would start here?

    Thoughts?

    Chris

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    Default Re: Mach 3 or Kflop buffering commands?

    What did the DROs show when the buffered motion happened?

    Also, if you open KMotion, what does the Axis screen show for each axis?
    I'm not aware that anything on the KFlop side would buffer motion, but if the Destination value is increasing after the reset, I'd guess the motion request is coming from Mach.

    Given the issue happened after the pendant stopped responding, I'd guess that's where the problem lies. I'm guessing that when the pendant has locked up, it's not received the command to flush any outstanding movement, or it simply doesn't flush any motion.
    It might be worth doing some testing by commanding a big move via the pendant, and then hitting E-stop before the move has completed, then seeing what happens when you reset Mach.



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    Default Re: Mach 3 or Kflop buffering commands?

    Could be the plugin for the pendant?

    Gerry

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    Default Re: Mach 3 or Kflop buffering commands?

    Hi Guys,

    Its so fast that I don't know what the DRO or Kmotion shows. I can try to catch it next time.

    Something else I noticed was I had a plugin for the old pendant enabled so maybe there is a conflict...

    The current pendant manufacturer claims there is no way commands are buffering on it.

    Cheers

    Chris



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    Default Re: Mach 3 or Kflop buffering commands?

    Hi Chris,

    Mach3 USB Pendents are not recommended. I'm surprised it works at all. I'm not familiar with that one.

    But it may be how you are initializing your system and configuring the axes. For example it could be you are initializing the target Destination to where it was commanded last rather than where it currently is. In that case if the system had been commanded to move someplace and prevented from moving for whatever reason (Drive disabled) then when re-Initialized it would try to servo to that previous position in a violent manner. If the Max Following Error is set to a small value then the axis should immediately disable. But if not, the Axis will move to the target destination.

    Initializing axis 0 to set the target destination to where it currently is at (no motion) can be accomplished with:

    EnableAxisDest(0, ch0->Position);

    HTH
    Regards

    Regards
    TK http://dynomotion.com


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    Default Re: Mach 3 or Kflop buffering commands?

    Hi Tom thanks for the reply!

    I will look at the Max following error and also check on the initialization. I do disable the axis on Estop so shouldn't that reset the commanded position when re initialized? Do I add that command to the init c program under each axis (same area where the PID parameters are etc?)

    For a pendant can you recommend one you have seen used with kmotion before? So I would connect it to kanalog directly then?



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    Default Re: Mach 3 or Kflop buffering commands?

    Hi Chris,

    Its your choice on how to set the commanded destination when you enable the axis. It usually makes most sense to set it to the current Position.

    You probably already have Enable statements in your Initialization. You would just want to look at what they do and possibly modify them. An axis can be enabled anytime after all its parameters have been configured and whatever else is required for your system (ie enable Drives).

    Regarding Pendent see our wiki here:
    Dynomotion

    Regards

    Regards
    TK http://dynomotion.com


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    Default Re: Mach 3 or Kflop buffering commands?

    Hi Tom,

    I have attached my original Init and my new Init script. Can you have a quick look at them and tell me if I missed anything. I changed the EnableAxis to EnableAxisDest and reduced the following error.

    I was still getting the issue occasionally even with those changes so I unplugged the pendant and so far have not seen the issue.

    Cheers

    Chris

    Attached Files Attached Files


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    Default Re: Mach 3 or Kflop buffering commands?

    Hi Chris,

    That looks correct except 15000 counts is still an abnormally high Max Following Error. I doubt if that would cause abnormal buffered motion.

    Regards

    Regards
    TK http://dynomotion.com


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    Default Re: Mach 3 or Kflop buffering commands?

    Ok very odd, the problem when away when I removed the pendant from the system. Lately I have been working on a way to keep the drives disabled until Mach 3 was up (see http://www.cnczone.com/forums/dynomo...op-wiring.html) and I decided to switch the enable signal to the drives powersupply using an enable signal from Mach.

    This worked and kept the axis disabled (to eliminate drift) until Mach was started and taken out of reset but for some reason the Z axis will dive down when reset is hit in Mach 3 with no command until it trips the max following error and stops. Kmotion then shows Axis 2 disabled, hit reset in Mach 3 again and it dives down and trips on Max following error again. This repeats again and again, only way to fix it is to put it back the way it was where the power supply enable was driven by the estop and disregards Mach 3 status. I need to fix this as in that state the axis all drift slightly.

    I checked in the console in Kmotion and it shows Following Error Disabled Axis:2

    First trip - Dest = 1, Position = -20976
    Second trip - Dest=-20976, Position= -35071
    Third trip - Dest= -35071, Position= -48490
    Fourth trip - Dest = -48490, Position= -62414
    Fifth trip- Dest= -62414, Position= -85997

    etc etc

    Following error is set to 5000 for Axis 2

    Not sure if it matters but Z axis also has a physical brake which is driven by the same enable signal could that have an effect?

    Thoughts?

    Cheers

    Chris



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    Default Re: Mach 3 or Kflop buffering commands?

    Could the axis be dropping under gravity when the brake is released?
    When does the servo loop get enabled in relation to the brake being released?



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    Default Re: Mach 3 or Kflop buffering commands?

    The Servo loop enable and brake release occur at the same time.

    Cheers

    Chris



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    Default Re: Mach 3 or Kflop buffering commands?

    What does the axis screen in KMotion show when you initialise Mach?

    To me it's like there is a commanded move being generated somewhere.
    Might be worth attaching your latest init, and mach xml file.



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    Default Re: Mach 3 or Kflop buffering commands?

    Prior to initialization the Axis screen shows 0 for Dest and close to zero for Position (most i saw was 12). All axis disabled.

    I will get and post the init and xml file Sunday.

    Cheers

    Chris



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    Default Re: Mach 3 or Kflop buffering commands?

    And what happens with the destination/position during initialisation?

    Do you think the axis is being powered downward, or dropping under gravity?
    It can be quite surprising how easily/quickly quills/heads will drop under gravity. It could be worth trying to apply a bit friction to the ballscrew/motor/belt so it definitely can't move just by gravity.



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    Default Re: Mach 3 or Kflop buffering commands?

    I will check, but if it was falling under gravity wouldn't it try to correct upwards instead of driving it downwards? I do see the feedrate in Mach go to 120 briefly which is the max speed so it appears to be driven.

    Cheers

    Chris



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    Default Re: Mach 3 or Kflop buffering commands?

    Hi Chris,

    You might post your Initialization Program so we can see how things are being initialized and handled.

    You might also observe the KMotion Axis Screen's Commanded Destination and Encoder Position before and after initializing and the motion downward.

    One possible scenario is that your Z axis servo doesn't have any Integrator gain and because of gravity the actual position is significantly below the commanded position. Normally when enabling the axes the target Destination is set to the current Position as an attempt not to move much. However in this scenario the result will be a step downward each time the system is initialized. For example say the Commanded Position is 1000 but due to gravity the Position drops to 900. If the system is re-initialized and sets the Commanded position to where it is (900) the position will then drop to 800.

    HTH
    Regards

    Regards
    TK http://dynomotion.com


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    Default Re: Mach 3 or Kflop buffering commands?

    Init program is posted above (init_new.txt) only change is I have been adjusting the max following error.

    I will take pics of the Axis screen tomorrow.

    Cheers

    Chris



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    Default Re: Mach 3 or Kflop buffering commands?

    Ok, after playing with it some more and manually releasing the brake to see how fast the z axis moves down under gravity I am leaning more and more towards the control loop/drive power is not fast enough to catch the initial drop of the Z axis when the brake is removed. So either I need to power the drives and enable control then wait a second before releasing the brake or I need to speed up the response of the control loop (assuming the drive enable gets power to the drives fast enough).

    I have attached pics of the axis screen on a fresh restart and when it faults after the first and second reset in Mach. Also attatched is the current init program and a console capture.

    Cheers

    Chris

    Attached Thumbnails Attached Thumbnails Mach 3 or Kflop buffering commands?-mach-reset-1-jpg   Mach 3 or Kflop buffering commands?-pre-enable-jpg   Mach 3 or Kflop buffering commands?-mach-reset-2-jpg   Mach 3 or Kflop buffering commands?-console-jpg  

    Attached Files Attached Files


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    Default Re: Mach 3 or Kflop buffering commands?

    Do you have a link to a manual for the servo/drives?



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Mach 3 or Kflop buffering commands?

Mach 3 or Kflop buffering commands?