Noise issue

[jackgiz]

Hi Tom,
It's been awhile since I last posted because my Kflop has been running great since 2014.....until I decided to upgrade my CNC router with a spindle. With KmotionCNC running and the inverter powered on I can move the all 3 axis without a problem. Within a couple of seconds of pressing the run button on the inverter all 3 axis DRO's turned yellow, never got to jog or run any program. I read another post about a similar issue and decided to check out my switch input shield grounding. I found 1 switch input shield wire that had come loose. (I'm using simple SPDT micro switches on my X,Y & Z connected to JP6.) I reconnected that one shield to my Kflop common (like the other shields) and had some improvement. I could hit the run button on the inverter and jog each of the axis several times before the X,Y & Z would turn yellow. Hitting the Init button would reset the DRO's and I could again jog each axis before it would die again. The power cable to the spindle is at least 18" away from any other stepper or switch input wiring. I have not yet tried to automate the start/stop/variable speed features of the inverter so none of that is connected to the Kflop/Kstep.

I have a USB isolator on order and I'm thinking of adding a .01 or .001 uF cap across each switch input close to the Kflop. My 15ft UBS cable doesn't have any ferrite cores so I was thinking to upgrade and shorten that cable too. Is there anything else I should consider doing while I'm at it?

Jack

[TomKerekes]

Hi Jack,

I would monitor the KMotion.exe Console Screen for messages on what is disabling the Axes.

Its a bit strange that all 3 axes are disabled. Do the axes have separate limit switches? Are the switches opto isolated 24V?

Do you have any other inputs to KFLOP such as an EStop signal?

If the issue was the USB communication I would expect a Disconnect Error not just Axes disables.

[jackgiz]

Hi Tom,
Noise is an interesting problem to solve and it seems like it's never one thing.

Yes I have an Estop and made sure the shield was grounded. No improvement.

All of my inputs (X, 2 for Y, Z, Estop, Touch Plate) feed into J33 opto isolated inputs on Kstep using 12V. I unplugged the ribbon cable from the breakout broad to disconnect all inputs. No improvement.

I noticed that none of my stepper cable shields were earth grounded. Did a quick grounding with alligator clips. Major improvement but still had axis disable issues.

Noticed that I have the spindle earth grounded through the inverter through a 220v line back the the breaker panel. Also had a 110v receptacle in a metal box attached to the gantry (for the router before this upgrade) that ran parallel to the 220v line back to the breaker panel. That must have created some ground loop interference because once I isolated the 110v receptacle from the gantry the issue seemed to go completely away. Even using my 15 ft USB cable with no ferrites. However, as soon as I plugged in the video cable from my PC to my monitor I got a read/disconnect error. Apparently the monitor grounds the PC. I'm hoping the USB isolater that I have on order will fix that problem.

I was able to successfully run a program using manual control of the inverter with no issues.

Do you think I should add any capacitors to the inputs for added insurance? (and yes, I will get rid of the alligator clips and hard wire)

Next will be interfacing my Kflop with the inverter through a C6 interface board. There was a pretty good post on how to do that so I'll start there and see how far I get.

Thanks for your help.
Jack

[TomKerekes]

Hi Jack,

All of my inputs (X, 2 for Y, Z, Estop, Touch Plate) feed into J33 opto isolated inputs on Kstep using 12V. I unplugged the ribbon cable from the breakout broad to disconnect all inputs. No improvement.

Strange? That would indicate noise between KStep and KFLOP? How long is that ribbon cable?

So it is still not clear what is disabling the Axes. No messages on the Console? I'm thinking you have a loop monitoring the EStop input and that is causing the disable. If you remove the code to do that do the axes still disable?

However, as soon as I plugged in the video cable from my PC to my monitor I got a read/disconnect error. Apparently the monitor grounds the PC. I'm hoping the USB isolater that I have on order will fix that problem.

I think there would still be a ground loop. But it may help.

Do you think I should add any capacitors to the inputs for added insurance?

I don't think that should be necessary. KStep opto inputs are relatively slow so provide hi frequency filtering naturally.

Next will be interfacing my Kflop with the inverter through a C6 interface board. There was a pretty good post on how to do that so I'll start there and see how far I get.

You might also use the IO on KStep which is fully isolated.

[jackgiz]

Hi Tom,
Thanks for the quick response.

"Strange? That would indicate noise between KStep and KFLOP? How long is that ribbon cable?

So it is still not clear what is disabling the Axes. No messages on the Console? I'm thinking you have a loop monitoring the EStop input and that is causing the disable. If you remove the code to do that do the axes still disable?"

Ribbon is about 4" long. BOB sits right next to the Kstep.
There was no message on the Console.
I do have an Estop loop. I will remove the stepper sheild connections and comment out the Estop loop to see what happens.

"I think there would still be a ground loop. But it may help."

Plan B would be to use an adaptor to convert a 3 prong plug to 2 prongs on the external display.

Thanks for the feedback on the capacitors.

"You might also use the IO on KStep which is fully isolated."

Yes, I was going to use JP26 for CW/CCW and Speed

Related to noise - I currently have a 5/12V power supply connected to the Kstep. I have a separate 5V supply powering the Kflop (appropriate jumpers removed). The C6 requires a 12V supply. I'm thinking that I shouldn't use my 5/12V power supply to power the C6. The input side of the C6 has opto's but the analog output will have it's common connected to the VFD's common. It looks like there is a 12V/200mA source in the inverter. Do you agree that it would be better to use the VFD 12v source?

[TomKerekes]

Hi Jack,

Related to noise - I currently have a 5/12V power supply connected to the Kstep. I have a separate 5V supply powering the Kflop (appropriate jumpers removed). The C6 requires a 12V supply. I'm thinking that I shouldn't use my 5/12V power supply to power the C6. The input side of the C6 has opto's but the analog output will have it's common connected to the VFD's common. It looks like there is a 12V/200mA source in the inverter. Do you agree that it would be better to use the VFD 12v source?

I agree. I think using KStep's 12V would defeat the isolation between KStep and the Inverter. KFLOP would still be isolated from the Inverter which is probably more important, but if you can keep the Inverter isolated from KStep as well why not?

[jackgiz]

Hi Tom,
Noise issues can drive you nuts. Yesterday I couldn't get my machine to fail. Today, every time I started the spindle the X, Y and Z axis would turn yellow. I did have an Estop loop. I commented the loop out of my init program like you suggested and the disables stopped so the noise was definitely coming through the Estop input (probably the other switch inputs too they just didn't disable the axis). I tried moving things around, checked all the grounds again, tried adding a by pass cap. Nothing would help. I finally thought about changing my Estop from a normally open to a normally closed switch. I changed the wiring and changed the program and the disables stopped. All of my switch inputs are normally open so I'm going to change them all to normally closed. Normally closed seems like a better, fail safe method anyway.

Got my spindle to start and stop with Kmotion. Still have spindle speed issues but that's tomorrow's problem.

Jack

[jackgiz]

Hi Tom,
I have my spindle starting and stopping from Kflop JP5. When I switch to Kstep JP26 I get nothing. I read that I have to enable the amplifiers on Kstep. I have separate 5volt supplies for Kstep and Kflop. Do I connect a jumper from Kstep JP6 enable to Kstep 5v? Kstep Ground? or Kflop Ground?

Thanks,
Jack

[TomKerekes]

Hi Jack,

Sorry I'm lost.

I have my spindle starting and stopping from Kflop JP5. When I switch to Kstep JP26 I get nothing.

How can you do this? KFLOP JP5 have Step/Dir LVTTL outputs. JP26 has no Step/Dir outputs and has relay driver outputs (basically switches). Totally different.

I read that I have to enable the amplifiers on Kstep.

That's for the Stepper Motor Drivers not JP26 IO.

I have separate 5volt supplies for Kstep and Kflop.

Is that something you changed?

Is KStep connected to KFLOP JP7?

[jackgiz]

Hi Tom,
Well I guess that explains a few things. I saw Step and Dir on JP26 and assumed that I could use those points to drive my spindle. I misunderstood the documentation.

I've had separate power supplies since day one. The reason I mentioned it was so I didn't screw something up when trying to fire up the enable pin which is an non issue now since that won't work.

Kflop is connected to Kstep through JP7.

So back to an earlier response from you when I said I wanted to control a spindle you suggested "You might also use the IO on KStep which is fully isolated." Where/how would I do this? or should I just leave well enough alone and stick with JP5 (I/O 39,40 & 41)?

Thanks,
Jack