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IndustryArena Forum > CNC Electronics > Dmm Technology > DYN4 Overcurrent, but only on initial startup
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  1. #21

    Re: DYN4 Overcurrent, but only on initial startup

    Quote Originally Posted by mactec54 View Post
    With your jerry rigged incremental linear encoders system you use anything is likely to happen we where not talking about incremental encoders

    Absolute is the name of the game
    Jerry rigged? Never had a problem on the machine with the linear encoders, it works flawlessly and has for years. That subject was about losing position. That's why I separated the quotes.

    The DMM problems were on machines using the DMM encoders, and no linear encoders. But I admit I was wrong, I identified the DMM single turn absolute encoder as an incremental. I have never used the DMM multi-turn absolute units.
    Jim Dawson
    Sandy, Oregon, USA

  2. #22

    Re: DYN4 Overcurrent, but only on initial startup

    Quote Originally Posted by mactec54 View Post
    Yes you could do it like that seeing you already have the PLC as part of your system, but at no time the machine is in run mode should the logic be able to disconnect only at power down of the machine
    Okay I think I'm following now. I won't implement anything that would cut power to the logic circuit prior to shutdown.

  3. #23

    Re: DYN4 Overcurrent, but only on initial startup

    I spent a few hours messing with it last night. Shielded cables for logic power don't help (but I have some really nice cables now), neither did getting power from elsewhere in the cabinet or outside of the cabinet. If noise is causing or contributing, I don't think it's coming from the logic power.

    I did notice that the issues seemed to follow a couple of the control/drive cables. I've been removing them and reinstalling with no regard to which drive they were on so it wasn't obvious at first. Closer look at them shows there are some problems. I suspect there is a "split pair" condition as well as some encoder & pos signals swapped. Not sure if this is causing all the issues but I hope to correct and test again today.

  4. #24
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    Re: DYN4 Overcurrent, but only on initial startup

    Quote Originally Posted by Sam_Beckham View Post
    I spent a few hours messing with it last night. Shielded cables for logic power don't help (but I have some really nice cables now), neither did getting power from elsewhere in the cabinet or outside of the cabinet. If noise is causing or contributing, I don't think it's coming from the logic power.

    I did notice that the issues seemed to follow a couple of the control/drive cables. I've been removing them and reinstalling with no regard to which drive they were on so it wasn't obvious at first. Closer look at them shows there are some problems. I suspect there is a "split pair" condition as well as some encoder & pos signals swapped. Not sure if this is causing all the issues but I hope to correct and test again today.
    How have you Grounded your shields they won't work as shields if they are terminated incorrect
    Mactec54

  5. #25

    Re: DYN4 Overcurrent, but only on initial startup

    I used a solder sleeve to attach a small wire at the drive end, it's attached to one of the ground lugs on the front of the drive. That lug is grounded through another larger wire to the ground bar where power comes in.

    I just got the cables reworked. Only slightly mangled one contact. Working with those little buggers is making it apparent that my eyes aren't what they used to be. Hoping that helps resolve this issue without having to resort to staging the power up.

  6. #26

    Re: DYN4 Overcurrent, but only on initial startup

    Well no dice there. They turn the right direction now but still fault out. In fact, it seems the more I play with them, the more they are faulting out. I'm getting faults now when I play with them for a while and then let the drives sit idle with e-stop engaged, as soon as I pull it out one or more will fault.

    They bench tested fine so it has to have something to do the with the controller communication. I either have too much noise or cables that are too susceptible to noise, or both.

  7. #27

    Re: DYN4 Overcurrent, but only on initial startup

    I assume pulling the E stop energizes the drive contactors? Do you still have the drive logic wired around the contactors?
    Jim Dawson
    Sandy, Oregon, USA

  8. #28
    Quote Originally Posted by Jim Dawson View Post
    I assume pulling the E stop energizes the drive contactors? Do you still have the drive logic wired around the contactors?
    Yeah I still have them wired around the contactors. I’m more concerned now that they are faulting out after the control is running. Maybe I should just run it all through the contactors and get used to homing it all the time. It’s moving at over 1000in/min maxed out so I guess it can home pretty quickly if it needs to

  9. #29

    Re: DYN4 Overcurrent, but only on initial startup

    You might give rewiring a try and see if it makes a difference. At least it would eliminate one possibility.
    Jim Dawson
    Sandy, Oregon, USA

  10. #30

    Re: DYN4 Overcurrent, but only on initial startup

    I don’t think it would have a chance to happen if logic was wired through the e-stop too. I’m pretty much ready to give up and go that way.

    Maybe I’ll give it a try and move on to getting the spindle and atc working. If it bugs me I can always circle back and mess with it later.

  11. #31
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    Re: DYN4 Overcurrent, but only on initial startup

    Quote Originally Posted by Sam_Beckham View Post
    I used a solder sleeve to attach a small wire at the drive end, it's attached to one of the ground lugs on the front of the drive. That lug is grounded through another larger wire to the ground bar where power comes in.

    I just got the cables reworked. Only slightly mangled one contact. Working with those little buggers is making it apparent that my eyes aren't what they used to be. Hoping that helps resolve this issue without having to resort to staging the power up.
    That's a bad idea to add a pigtail to a shield that renders the shield almost ineffective and carries the noise on the unshielded wire, they must be direct Grounded to be affected here are some example's of how it should be done and how ineffective using /adding wire to a shield is, there should be no soldering of the shield just direct clamping contact to the Ground plane
    Mactec54

  12. #32

    Re: DYN4 Overcurrent, but only on initial startup

    Single point drains have a place. You look like you’ve been studying up on terminating RF transmission lines.

    I’m going to rearrange some stuff in the cabinet. I really wanted to terminate the shields on the other end, at the filters, but I’m short a couple of terminals. I also want to move the filters right next to the drive so they aren’t routed anywhere near the contactors.

    I doubt any of this is going to fix the problem, at least very robustly. I have a couple ideas but they will have to wait until I have some better test equipment on hand. I’m really suspicious that the enable line is just floating during the initial start up. Nothing short of some direct intervention with the line levels is going to fix that.

  13. #33
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    Re: DYN4 Overcurrent, but only on initial startup

    Quote Originally Posted by Sam_Beckham View Post
    Single point drains have a place. You look like you’ve been studying up on terminating RF transmission lines.

    I’m going to rearrange some stuff in the cabinet. I really wanted to terminate the shields on the other end, at the filters, but I’m short a couple of terminals. I also want to move the filters right next to the drive so they aren’t routed anywhere near the contactors.

    I doubt any of this is going to fix the problem, at least very robustly. I have a couple ideas but they will have to wait until I have some better test equipment on hand. I’m really suspicious that the enable line is just floating during the initial start up. Nothing short of some direct intervention with the line levels is going to fix that.
    Single point drains don't have a place and never will, been doing this to long to know better RF transmission lines have nothing to do with this, what I posted is industry standard that I used examples of

    Shields should always be terminated at the source for analog signals 360 degree clamp termination, all others shields need to be terminated at both ends 360 degree clamping

    It sounds like you may have many different wiring problems, your starters are a bad source for spikes and EMI do you have snubbers on the starters / contactors ???

    How are you powering your system single phase 240v or 3 phase 240v and what is your supply source ???

    Can you post some photos of your cabinet I might see something that can easily be corrected
    Mactec54

  14. #34

    Re: DYN4 Overcurrent, but only on initial startup

    I’ve got everything pulled out between the line reactors and drives now. I’m trying to figure out a way to put the filters and contactors back in that will facilitate switching the wiring to the way Jim has his (if need be). That’s plan B but looking more and more likely that it’s reality at this point. I’m not happy about that but it’s where I am now since these servos aren’t designed to operate with logic on all the time.

    My plan is to mount the contactors right under the line reactors, run plain old non shielded single wires between them. Then the row of filters under the contactors, right above the row of drives. Still working on the plan for logic vs power wire routing.

    All of the OEM cables in this machine have the dreaded single point shield terminations including the VFD cable. Even the centroid cables were built that way.

    Snubbers. I have snubbers on everything to include the contact coils. I even changed those out just to make sure.

    I can post a picture of the cabinet before taking all this stuff out to give you an idea but I’ll have to do it from my computer I think. Not seeing the attachment options on my phone right now.

    ETA: Everything is powered from 240 single phase. 6 ga wire straight to the service panel. Line voltage seems really stable, even when powering up the drives it stays within .2v. I did not run a neutral to the cabinet so all I’ve got is the 240 and the derived 120 & 24 vac from a 750 VA transformer. That’s just there to run the contactors and the 120v fans and transmission pump/cooler.

    ETA2:

    https://drive.google.com/file/d/16tVaZ8j6PjY2-b063a35LFyKdN7Xndzc/view?usp=drivesdk

    You can see how I jammed the filters in there as an afterthought. I’m working on straightening that out.

  15. #35
    Here’s where I am now

  16. #36
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    Re: DYN4 Overcurrent, but only on initial startup

    Quote Originally Posted by Sam_Beckham View Post
    Here’s where I am now
    Are the filters for the 240v single phase main power or the logic

    I have always wired them having the logic separate never had a problem so don't know what is really going on, the logic drops down to 15v inside the drive so does not care how it is feed as long as it has a EMI filter on the feed line, remember twist all wire pairs this will help a lot in tight spaces like what you have

    I would of only used ( 1 ) reactor for all the drives and ( 1 ) contactor, if you are doing a 4th axis then I do that separate, each always should have there own breakers but still only ( 1 ) line conditioner ( reactor ) and Filter needed for the whole system, the reactor and filter and contactor need to be rated for max possible current

    The logic circuit also only needs to be ( 1 ) circuit for all the drives, so ( 1 ) Filter ( 1 ) breaker or fused, this cuts down on wire and possible problems, always twist Main Power wire pairs where ever you can this can help cut any noise

    You can't compare or use much of your old system once you change one thing then what work before will not work the same again, so don't rely on any of the old connections as they will be trouble

    The Dmm system is normally very good as far as EMI noise goes I can't say the same for any electronics that you are using as I have not used the OAK system
    Mactec54

  17. #37

    Re: DYN4 Overcurrent, but only on initial startup

    Yeah the filters are for the logic power lines only. DMM schematics (for the Oak specifically) showed separate logic filters for each drive, as well as separate contactors. I like the idea of consolidating at least the logic power into one circuit. I may try just using the extra 4th axis contactor to power all of the logic lines. I can then switch it from being on all the time to powering up when enabled, or whatever, at least while I'm testing things. I will make sure and twist up the logic wires.

    The multiple reactors wasn't the initial plan. I won't bore you with the evolution of that mess but I don't think they will hurt anything other than, as you said, there is a little more complexity there than need be.

    The latest from DMM is that they suspect a timing issue with the Oak communication, specifically the enable. I want to at least do my due diligence to make sure I'm addressing noise in the cabinet, but I have suspected the enable line from the beginning. I think I know what's going on but I don't have the equipment I need here to say for sure.

    DMM literature indicates that the enable INPUT is an open collector input. Centroid install manual indicates that the enable pin is an open collector output which isn't going to do anything but pull the line low when enabled. I'm not seeing how the enable line isn't just floating there prior to the Oak pulling it low. Oak doesn't even assert the low level until it's ready to command movement from what I can tell. The servos will sit with free shafts after start up, until an axis movement is commanded.

    I'm tempted to jumper the enable line to the +24v pin through a resistor and see what happens. If it's really being caused by a floating logic line I think that would make it go away.

    ETA: Nevermind that last part. I looked in the DMM manual and the ENA input appears to be connected to the +24V pin through a 3k resistor internally. So it really should be high until the Oak pulls it down.

  18. #38

    Re: DYN4 Overcurrent, but only on initial startup

    I understand the need to get the servos under control and certainly stop them from faulting on power up. But I wonder if the the E stop/position loss issue is a real problem.

    My normal operation mode is to start and home the machine and not hit the E stop again until I'm done for the day at shut down. The E stop is there in case there is an actual problem. On one machine I have a seperate button to enable/disable the servos, leaving the drives powered up but disabled.
    Jim Dawson
    Sandy, Oregon, USA

  19. #39

    Re: DYN4 Overcurrent, but only on initial startup

    Loosing the encoders wouldn’t be a big deal if I never hit the e-stop I guess. Things not working the way they are supposed to bugs me but you are probably right. I would be making chips with it right now if I had just taken DMM’s advice and wired everything through the contactor.

  20. #40
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    Re: DYN4 Overcurrent, but only on initial startup

    Quote Originally Posted by Sam_Beckham View Post
    Yeah the filters are for the logic power lines only. DMM schematics (for the Oak specifically) showed separate logic filters for each drive, as well as separate contactors. I like the idea of consolidating at least the logic power into one circuit. I may try just using the extra 4th axis contactor to power all of the logic lines. I can then switch it from being on all the time to powering up when enabled, or whatever, at least while I'm testing things. I will make sure and twist up the logic wires.

    The multiple reactors wasn't the initial plan. I won't bore you with the evolution of that mess but I don't think they will hurt anything other than, as you said, there is a little more complexity there than need be.

    The latest from DMM is that they suspect a timing issue with the Oak communication, specifically the enable. I want to at least do my due diligence to make sure I'm addressing noise in the cabinet, but I have suspected the enable line from the beginning. I think I know what's going on but I don't have the equipment I need here to say for sure.

    DMM literature indicates that the enable INPUT is an open collector input. Centroid install manual indicates that the enable pin is an open collector output which isn't going to do anything but pull the line low when enabled. I'm not seeing how the enable line isn't just floating there prior to the Oak pulling it low. Oak doesn't even assert the low level until it's ready to command movement from what I can tell. The servos will sit with free shafts after start up, until an axis movement is commanded.

    I'm tempted to jumper the enable line to the +24v pin through a resistor and see what happens. If it's really being caused by a floating logic line I think that would make it go away.

    ETA: Nevermind that last part. I looked in the DMM manual and the ENA input appears to be connected to the +24V pin through a 3k resistor internally. So it really should be high until the Oak pulls it down.
    Twist the Power wires as well, the 2 hot wires, never twist in a Ground wire they are just as important as the logic lines, especially if you don't have much space
    Mactec54

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