[Lapin]

Hi.

I am trying to get my cnc run stable. My setup is 4 VSD-XE connected to an VSDEPI which are run by a SmoothStepper. Motors are from Anaheim Automation 3x these, the 48V version and one of this 48V too. The encoders are form the same supplier and made by USDigital.

The problems i have is that every time i start up the system it behaves differently. Sometimes i can get it to run smoothly, and the next time it will set the drivers in error state even when the only thing i did was to restart the system.

Yesterday i got the Z axis to run good but when i try to jog the X axis (which are dual driven) the motors bump and puts the drives in error. I cut of the power, restart mach and try again, this time with the X axis first. It behaves in the same way just the other way. X runs great but when i try Z after the motor bumps and the drive go to error.

Today i tried again but this time i was not able to drive any axis, the drive goes to error when i just pressed the jogbutton for Y axis whitout any sign of movement even. The X axis Bumps quite hard and sets both drives to error.

I cant understand why it behaves like this when i did not change anything in the setup from time to time, only restart the system.

My thoughts is that maybe the encoders are failing, some kind of noise or so, cus i heard that some have problems with USDigital encoders. My other guess is that it have something to do with the SmoothStepper or some other noise issues? The motor and encoder cables are high quality from IGUS with good shielding.

Any ideas what i should try to get it working properly? I have asked around in the swedish forum but they ran out of ideas, so im in a dead end state right now with my build.

Thanks

[Lapin]

And now just recently when i wass gonna try run em straight from the PPort i get undervoltage faults on all drives. I have checked the fuses and measured voltage to ~70 VDC to the drives. In GDTools the limits are set to 20000 to 170000 range. This driving me nuts (nuts)

[Xerxes]

Hi Lapin,

Could you post step response graphs of torque tuning and position tuning? Also please share the saved .drc file so I can check if some settings seems wrong.

My best guess is that there's just some issue in configuration, so it barely works and then fault seems to happen in random way.

The undervoltage fault really means that drive measured voltage that is out of your configured 20-170V range. What kind of power supply do you use? Please specify the transformer and filter capacitors sizes you use. I photo also would be great :-) Dropping supply voltage could be also the source of errors.

[Lapin]

The thing is that i have about 400 Km to where my machine is located as i work in another place. I can only work with the machine when i get time of from work a longer time, vacation etc. So unfortunately i cant show you any graphs at the moment. I will contact you tho when i manage to get there.

I think its strange that i get undervoltage when i measure with a voltemeter just before it goes in to the drives, and there i have ~70 VDC.
The transformer is an 1600 VA 2x 48V, see pic, and the cap is one 47000uF / 100 V

Ill post pictures to on my PSU (note that its the first time i did something like this and i have just little experience with electrical stuffs, had alot of help from the swedish forum tho). Blue wire is Live line/+ and black is always null/- in this setup (i know thats the other way but im used to computers where black is always - so i did like this so it would be easy for me to remember).

[Xerxes]

Thanks for photos! That's very nicely done installation.

It's hard to believe that there would be undervoltage problem with such large power supply. How did you verify that it's undervoltage? Did it happen when using GDtool, so you could check status bits from software or did you rely on led blinking indications?

Is there any components between the main capacitor and drive HV inputs (or just straight wire)?

[Lapin]

Thanks Tero

Ye its a bit strange cus i have never had any problems with the voltage before when i tested the system. The leds indicates high/low voltage and when i check status tab in GDTools its shows that their is undervoltage.

Its a straight wire from the cap, nothing in between. I also have a softstart on the PSU that rises voltage over a few secs. I have checked all relays and fuses and they are all ok so it must have something to do with the drives.

[Xerxes]

Does it go into undervoltage in fast accelerations only? That's when most power is drawn.

You could do some GDtool step response testing and choose "HV bus voltage" channel to be captured. Then you'll see what drive sees in HV bus during motion.

[Lapin]

The thing is that i cant even get it to good voltage before i run. I turn on logic supply first, then i have a enablebutton which i press to get full voltage on HV bus. The leds, on logic only, shows undervoltage but when i press on the enablebutton the leds switch to static blue as it suppose to. But now it never switches to static blue light, it just keep on blinking red and blue thus i got about 70 V to the drives.

[Xerxes]

Have you tried turning on logic power after HV? Also have you checked drive fuses?

[Lapin]

I can try that maybe when i get to my machine the next time, i checked the fuses on drive with an contact beep signal and it beeps when i hold at each end of the fuse so i suppose its not broken, but there is cheramic fuse type, right? So maybe i need to replace them anyway? I dont know how they work.

[cobree]

What is the settings for your motor on GD tool General settings / Limits. Also make an reset drive at startup with tool, to see if that help " Device/ reset drive".

// Conny

[Xerxes]

I can try that maybe when i get to my machine the next time, i checked the fuses on drive with an contact beep signal and it beeps when i hold at each end of the fuse so i suppose its not broken, but there is cheramic fuse type, right? So maybe i need to replace them anyway? I dont know how they work.

The fuse is normal, no matter if it has ceramic or glass tube. Sometimes fuse holder is loose and need to be "tightened" to make electrical contact.

Is the voltage fault same in every drive? If true, then it's unlikely that every fuse has blown or loose.

[evo4wrx]

I can pretty much tell you exactly what your problem is....

I had a similar setup try the following.

Get a powered USB hub
Connect the VSD EPI and the smooth stepper into it.

All your problems will go away.

[Lapin]

The settings for the motors is alright i think. Checked it several times.
Ok, so it shouldnt be the fuses then cus all 4 drives indicate the same undervoltage.

evo4wrx: Did u had the strange motor behavior or the undervoltagefaults? Its really great if its just a powered usb hub thats needed to solve my problems on that front.

I think the undervoltage faults appeared after i physically pressed E-stop when my two motors on the X axis ran away uncontrolled, im not sure thou. But it shouldnt happen anything then right? The E-stop shuts down HU power only.

I appreciate your help. It would be great to have many different things to try which can solve the problems due to my long distance relationship with my machine

[evo4wrx]

I had a lot of different random faults...under voltage being one of them.

I went through the machine thinking it was noise , motors, encoders you name it. In the end I put a powered USB hub in and everything just went perfect.

[Lapin]

That sounds really promising. I will buy a usb hub and try later. I really hope it solves my problems and that i dont need to buy new encoders. Im just curious, how did u come up with that idea?

[evo4wrx]

The 5v USB ports only have a limited amount of current. They become quite unstable on even 1 encoder withe decent pulse rates and can pretty much drive a single port to its current limit. Mach3 / the computer and everything else just seems to really unstable and just heaps of random things keep happening.

With computers at least ive found a lot of people over the years say their computers are unstable. Ive found just by connecting a UPS up they become rock solid.

The surge and back currents from motors would almost be enough to destroy any stability.

[Xerxes]

Yes, USB hub is potential source of problems if power hungry devices are connected to it. However if devices are plugged directly to computer USB ports, it should eliminate the power problem because each port will be able to supply 0.5A current.

Lapin, if problem can't be fixed with the things mentioned in here, feel free to give us a call when you're near the machine. I'm sure the problem is fixable.

[Lapin]

Yes i will try a USB hub, the thing with an UPS is a good idea also.

I definitely think that the we gonna solve the problem, it just a matter of when. I will give u a call Tero if nothing mentioned works.

[NZCNC]

Hi there we have purchased these drives and a smooth stepper and are having probelms we have emailed the supplier several times and basically get no support for there products