Have you tried a new pp cable yet?
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Have you tried a new pp cable yet?
How can you confirm that it is a ground loop problem!! Have you confirmed that your PP cable is not just a printer cable (not all printer cables are the straight though type) You can check it with a multi meterQuote:
Originally Posted by eurikain
Is there a reason why you don't have an RFI filter on the VFD power lines close to the VFD?
Well, after trying to sort things out again with Graeme, we came to the conclusion that there was no ground loop. The PP cable is straight through, and there is nothing wrong with the 0V connections. So, I decided to take everything out of the control box, and next week I'll wire it step by step and check for interferences at each step.
Put in all in a metal box if you canQuote:
Originally Posted by eurikain
I need to find one first. Probably going to get a bigger cabinet so I have more room to work with. But beforehand I need to make things work.
I would power your VFD from a RFI filter such as this one http://www.ebay.co.uk/itm/RASMI-14A-...YAAOSw~OVWyKNV and put ferrites on your PP cable at each end - like these http://www.ebay.co.uk/itm/20-Pcs-Gra...oAAOSwCypWpz6J but you won't need 20 of them and you have to get ones that fit the cable.
Anyway - general question - Anybody know ? - do the better quality VFDs have RFI on the mains input ? and do the Chinese ones not have it ?
Hope this helps,
Cheers,
Rob
My Teco did.
It would trip the RCD in the 32amp wall socket though. It had an option to disengage it by snipping a wire.
Not related to interference but for safety - I was just looking at the 4th photo in post#1 ('dsc_0004.jpg') and noticed that the blue and brown cables going to the toroidal power supply appeared to be connected to incoming cables using male/female spade connectors. There looked like there was exposed metal on at least on of them.
If they are indeed the mains supply cables I don't think this is a good idea. Either put some heatshrink over each joint, or better still solder the cables together, heat shrink each individually, then heat shrink over both.
My ABB has one but like George it tripped the RCD. Thou mine was easier to disengage it was just remove a screw.
As they say, eyes like a sh#thouse rat. well spotted:thumsup:Quote:
Originally Posted by routercnc
I think the connectors are not fully pushed together. There are other mains connectors fully exposed though, like on the SMPS's for 12v and 5v.Quote:
Originally Posted by Clive S
So I unwired everything in the control box. Rewired separating power lines from control lines, and reducing enormously the amount of cables in there by chaining +5V and enable between the BOB and drivers. I now use 2 core shielded cable for the PUL/DIR signals. That made the wiring a heck more simple. Limits are not yet wired, homes neither, and the 24V PSU is not powered. Guess what ? Works like a charm !
So now I'm going to move forward step by step, making sure that each increment does not cause noise to appear.
Things look muuuuuuch neater now :) I'll keep you posted. As for the ferrites, I'll order some of them just as a safety.
Ok sounds good don't forget the pics:encouragement:
Expalin or show this please because if what sounds like this is not good.?Quote:
Originally Posted by eurikain
Hi Jazz,
I hope he means that the enable (-) are being daisy chained from the enable terminal on the BoB and that separately he is daisychaining +5v on the BoB to step(+) dir(+) and enable(+) on each driver (chained on to the next driver and the next and the next). It'll work (Hmmmm ?) but I don't think I would do exactly that.
Cheers
Rob
Rob is right. No worries, I meant "daisy chained". They each get 5V and the correct amount of amps. Same thing with the enable.
Bad news, I introduced noise again, then rolled back to the state I was in when I posted my first message, and now the noise is not going away. Same thing, though much better than it used it be: in the first second of the spindle starting to turn, as well as the last second before it stops, the steppers move a few steps.
I'll order a CSLab 4 axis motion controller today. Can anyone explain the following to me:
- Zapp Automation sells it for 335 Euros (shipping included) => 0 in stock, have to wait 7-10 more days
- CSLab sells it for 311 Euros (shipping included)
So, obviously I'd go for CSLab official's website.. or does anyone have a spare one to sell ?
You obviously have not rolled back fully. The questions are :-Quote:
Originally Posted by eurikain
1. Is the noise coming from your VFD - which it very much seems to be.
2. Is the propagation back along the mains cable or through the air
The probability is a bit of both. Filters and shielding before spending money on a motion controller.
I have, really, there's only the drivers, 5V and 70V PSU wired. The VFD is powered completely separately from the control cabinet. It's a different wall socket. Yes, it could be the mains. I need to call my local electronics store for help, I'm really lost now ^^. Can't deal with this myself.
Does your building have an earth supplied by the electric company or do you use earth rods in the ground. Are you still using the plastic control box? Pictures would help.Quote:
Originally Posted by eurikain
When you say the motors move a few steps when you turn on the vfd are they enabled and the motors locked when this happens?
I don't know the electrical safety regulations in Belgium, but I would guess they are much the same as in UK. I would expect the earth to be strapped to the plumbing although this is not necessarily a good ground contact with plastic pipes :stupid:.Quote:
Originally Posted by Clive S
Rob is correct that you shoudln't be spending money without sorting the problem. While the Cslabs are good with noise this doesn't mean it will cure your problem. The noise could be being picked up in number of places, the signal cables to drives for instance which are between Cslabs and Drives.
You NEED to find and remove the noise at the SOURCE. Buy mains Filter for both the Control box and the VFD before buying anything else.
Yes, the building earth goes to the electric company I believe. Standard setup here. I am actually not using any box anymore, it's all out of the box, screwed on a fireproof plate (not metal). I am sorry I haven't posted pictures. Here it is:
The X motor plates have been unmounted to prevent the gantry from twisting. The fireproof board is out of the box for easy access and testing.
Attachment 17947
All relays are not wired, there is no e-stop, no reset button, no contactor, not fans, no switches (only a switch on the power cord extension), no 24V power supply (Earth and Neutral are daisy chained with the 5V PSU, but there is no Load going to it as you can see).
Attachment 17933Attachment 17934Attachment 17935Attachment 17936Attachment 17937Attachment 17938Attachment 17939Attachment 17940Attachment 17941Attachment 17942Attachment 17943Attachment 17944Attachment 17945Attachment 17946
So, here is what happens:
1. drivers powered, Mach3 in reset mode, motors disabled, VFD powered, spindle off
2. click reset in mach3, motors are powered, enabled and locked
3. I can jog fine on each axis
4. press RUN on the VFD, spindle starts spinning right away. half a second after pressing RUN, I can feel (with my hand) and hear the motors move a few steps (ike 2-5 I would judge by feeling). Obviously I can't put my hands on all motors simultaneously, so I try one by one (the VFD is wired separately so I can carry it around with me).
5. press STOP on the VFD, same thing, right before the spindle stops spinning (so I would say in the lower frequency, around 500/1000 RPM), the motors move a few steps.
There are two parameters to the noise:
1. the time offset between the moment I press RUN or STOP. I guess this depends on the time it takes to get to the problematic frequency.
2. the number of uncommanded steps the motors move
If I press RUN, then wait until the spindle reaches the desired speed (100Hz), then press STOP, wait until it stops, and repeat this process a few times, I would say the problem occurs 7 times out of 10. The number of uncommanded steps and the time offset are always random.
Hope you can see things better now :)
Cheers,
G.
I can see one problem straight away. You have no main power to the BoB. In the (invisible) picture below the two middle connectors on the right are the main power (12 - 24v) for the BoB electronics. Without that you will get all sorts of random effects.
I tried to copy and paste from the pdf of the BoB manual, but it didnt work - anyway OP has BoB manual.
Hi G,
Here are some thoughts on interference in general. My machine was playing up recently with 'external e-stop requests' stopping the machine at random. Strangely the e-stop circuit (24V relay) had not tripped so all the drives were still powered etc. Basically either the BoB or PC/Mach3 had decided it had seen an e-stop signal from somewhere, or some noise, which it decided was an e-stop. This was a pain if you were cutting as it meant homing and 'start from here' messing about.
It could occur during cutting or even just jogging with the spindle on. I fitted an EMI filter in the invertor mains supply, but no difference. I then fitted a MeanWell mains powered DIN rail 5V supply to supply the BoB instead of a 5V feed from the PC, but no difference. I then used an extension cable reel to plug the invertor into a socket on the other end of the garage and then cut out a part without a problem. All the sockets in the garage are on the same ring back to the consumer unit but having some distance between the plugs seems to have helped. There were some unintended heavy cuts in there (including an accidental ~8mm DOC which snapped the 6mm carbide) and it still did not trip.
Going back to your BoB these are about £8 from China. I had one a year ago and it would not give out step/dir signals so in the end I swapped it out for a different make of board and all was well. You could buy one or two more cheap BoBs and give them a go before a major upgrade. They seem to be variable based on reading around and at that price you can see why.
Looking at your signal cables between the drives and step/dir on the BoB - you've used shielded cable, but I can't see if they are earthed?
I know the pins you are talking about Rob :) Even when the BOB is powered by the 24V PSU, there is still noise :(Quote:
Originally Posted by cropwell
I seem to remember that you can also power it through the USB socket. You could try this from the PC, if this works then longer term use a USB plug and lead but cut the cables, identify the power supply cable and wire it to an external 5V supply.
Hello routercnc,
Thanks for your message. It is very interesting what you are explaining. It's something I haven't tried yet, plugging the VFD into a complete different socket out of my room. As you can see on the pictures, the room is pretty small, so there might be something there.
You are right about the BOB's signal cables. STEP and DIR are CY-2 0.5mm^2. The shield is not earthed. I know I should, this was just really me trying to get minimal connections.
I think you're right with the process, as others have suggested. So here's what I think I'll do:
1. try power the VFD from a socket located in another "block" of my house (one that's on a different breaker circuit).
2. If the above doesn't work, I'll put an EMI filter on the mains of the VFD (or inverter as you call it)
3. If that doesn't help, I'll buy spare BOBs from China.
Yes, that's right, but there are two terminals made to replace the USB port, and I'm currently using them:Quote:
Originally Posted by routercnc
Attachment 17948
On the BoB OP is using the USB socket is connected by tracks on the board to the PC 5v and PC GND, so the USB socket is not needed.Quote:
Originally Posted by routercnc
But those shielded cables won't do much good if they are not earthed at one end.
This could be your problem. The BOB is tying PC ground thru the PP cable to GNd on the 5V supply. For test remove the 5V and power bob using USB.Quote:
Originally Posted by eurikain
Regards Spare cheap BOB's that's like simple adding 2+2=4.???. . . Crap + Crap = Crap so why bother.!
Okay this one also is a great idea ! That would explain why the noise does not appear when the PP cable is not connected ! I add this as first entry of my checklist.Quote:
Originally Posted by JAZZCNC
Always knew you were good at math :DQuote:
Originally Posted by JAZZCNC
Well, guys, problem solved ! Guess who was right ??????????
......
.....
...
JAZZZZZZZZZZ !!!!!
The 5V signal to the BOB had two routes to 0V... getting the 5V from the PC solves the problem :) This is why disconnecting the PP cable was causing the noise to go away, since it would suppress one of the two 0V possible routes.
Thanks for your help !
I do have one more tiny issue:
Mach3 controls the RUN/STOP signal and spindle speed fine, but the BOB seems to output an unstable signal for the spindle speed control. When running, the frequency can't stay still and keeps going up and down by 1-2 Hz, causing the spindle to run faster/slower (you can hear a slight increase/decrease in speed).
I can bypass this issue by disabling Mach3 speed control and only do the RUN/STOP, but while I'm at it, let's fix this issue if possible :)
Always helps with solving problems if you give us all the facts.!!. . . . . It's was a rather important bit of info you didn't make available, esp considering the BOB and been accused prevously.!Quote:
Originally Posted by eurikain
It's called Crap Bob Syndrome and I doubt there's much you can do for it.!!Quote:
Originally Posted by eurikain
You could try giving it an Asprin :whistle:Quote:
It's called Crap Bob Syndrome and I doubt there's much you can do for it.!!
Nah Bullet straight between the eyes works every time.:dejection:Quote:
Originally Posted by Clive S
You dorks :D
Well, a clue could have been that when the 5V PSU was off, its power LED was slightly on (not fully, but you could see some light), indicating that power was flowing from THE PC through to BOB to the 5V PSU (receiving -5V I guess).
Anyways, problem fixed, let's now move on to cutting !!!!
Quote:
Originally Posted by eurikain
Had you originally connected V- on your 5v PSU to GND ?
On your BoB the terminal marked PC GND is actually the current return path and should not be connected to GND but only to V- on the power supply. The BoB itself has a GND plane connection next to the 12-24v terminal, which is the current return path AND GND for the BoB electronics.
Yes that's what I had done. PC GND to 0V of the 5V PSU, and PC +5V to +5V of the 5VPSU.
Can you provide a quick diagram on how to do what you're explaining ?
Quote:
Originally Posted by eurikain
I trust you mean PC GND to -5v on the power supply.
On your power supply check with your meter for continuity between -5v and the earth terminal. It should not be connected internally in the power supply. If it is you will have a ground loop. These power supplies are generally not connected between the -5v terminal and the Earth terminal. Also make sure that if you use the 5v power supply that -5v is connected to PC GND on the BoB and nowhere else (I am assuming that you do not have any other requirements for 5v in your control box).
The Earth connection on the power supply should be connected to the star earthing point to provide shielding for the power supply.
In a conversation with Graeme, he thought that the power supply, if under loaded, may react badly to interference from the VFD and cause all manner of effects, in fact it could go unstable by itself. So even if you get the earth and current return paths right, you may still have problems as you are only driving the optos on the BoB.
Jazz hit on a solution, and the PC USB supplying 5v to the BoB is workable, but I do not like using USB ports to provide power as they have limitations.
If it is working now don't muck about with it, but I still don't believe that we have got to the root cause of the problem.
Cheers,
Rob