Machsupport Forum
Mach Discussion => Mach4 General Discussion => Topic started by: gme on November 20, 2019, 03:15:50 AM
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"Touch" module malfunctioning. I use the Makers Guide Triple Edge Finder to zero X, Y and Z axes working coordinates. The Triple Edge finder has a hole that centers over any of the 4 corners of a work piece. When I lower Z into the hole and execute the center finding function, the probe (in my case an end mill or steel dowel) moves in the usual sequence, i.e., -x, +x, -Y, and +Y. The probe starts out as it should; however, at one of 4 touches, it frequently faults. When a fault occurs, the probe touches and just stops and Mach4 goes into a disable state. What follows is a cut and paste of a history screen, which documents what happens. The fault occurs randomly and can occur at any one of the 4 touch points. The problem has also occurred when setting Z=0, but only 2 or 3 times.
X axis is performing a touch move.
ESS starting Probe 0
ESS: Successful Probe0 Strike. Probing finished.
X axis is performing a touch move.
ESS starting Probe 0
ESS: Successful Probe0 Strike. Probing finished.
Y axis is performing a touch move.
ESS starting Probe 0
ESS: Successful Probe0 Strike. Probing finished.
ERROR: No contact with probe
Note that history reports a touch (Strike) at -Y, but errors and reports no contact. In this case, the probe touched at -Y, stopped there and Mach4 when into disabled status.
Previously, I used Mach3 and the Big Tex Blue Screen, which had the same functionality. It worked fine. Never a problem. The problem showed up when I upgraded to Mach4. While the problem occurs often, it did not show up every time I run the center finding touch function. I sometimes have to run it 3 or 4 times until it runs correctly. Very annoying.
Can anyone help me with the fix.
Here is my system data: PDMX126 Bob, PMDX107 spindle control, ESS Smoothstepper. My computer is an HP laptop, 12 MB of ram, a fast processor and Windows 10. It is a dedicated to my CNC ops and is only connected to the internet for updates. When disconnected, I shut down all anti virus software. My CNC is a 4 x 4 gantry router running NEMA 34s on all axes. My spindle is properly grounded and has an incoming line filter. No noise related issues. More importantly, my VFD is rarely turned on when I am running the touch sequences, so it would not be adding any noise to the mix.
Thank you,
Gary
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Oh, one other thing. I have the latest version of Mach4 and ESS Plugin. The problem has been there from the beginning and across a number of updates.
Gary
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I have also had a similar issue with the latest version, 4338. I changed to an earlier version, 4322. My machine is working fine now.
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Thank you, David. I thought version 4322 was the latest version. It's the version I'm presently using, and like previous versions, is giving me the problem.
You said your issue was "similar." Could you describe the issue you were having?
Thanks,
Gary
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I don't remember the details exactly. When I was zeroing my machine using a script that I wrote that was working on many previous versions, it was having a failure when zeroing the tool (Z axis). It was having a failure before it hit the touch probe. I don't remember the error message. I then tried entering commands in the MDI panel. It would not move the Z axis; although it did home all axis.. The X and Y commands would work. Didn't spend much time troubleshooting. I switched to 4322 using the same Profile, Screen, and Modules. Everything worked.
I really don't know if 4338 or what was corrupt. Since you are running 4322, the issue that I had may be unrelated to yours. Also, I am running ESS plugin 250, and the AVID CNC BOB. (not the PMDX126.
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I don't remember the details exactly. When I was zeroing my machine using a script that I wrote that was working on many previous versions, it was having a failure when zeroing the tool (Z axis). It was having a failure before it hit the touch probe. I don't remember the error message. I then tried entering commands in the MDI panel. It would not move the Z axis; although it did home all axis.. The X and Y commands would work. Didn't spend much time troubleshooting. I switched to 4322 using the same Profile, Screen, and Modules. Everything worked.
I really don't know if 4338 or what was corrupt. Since you are running 4322, the issue that I had may be unrelated to yours. Also, I am running ESS plugin 250, and the AVID CNC BOB. (not the PMDX126.
Sounds like your issue was different than mine. You were using a script. I wasn't. I was using the touch module in Mach4. While yours wasn't touching, mine does. The mill/dowel makes contact with my touch plate and then stops and faults. When using the center finding function, it can move right and left for the X axis, then move to Y. It may touch at -Y and stop/fault. Or, it may move one way or the other on X and stop on contact and fault. In other words, it may touch, stop and fault at any of the 4 points of contact. The same sometimes occurs on the Z touchoff. The axis goes negative, touches and stops and faults. It does not retract as it's supposed to.
Despite the differences, I do appreciate your weighing in. Thank you.
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Sounds an awful lot like you have a noisy probe input.
But this says you do not have the settings in the touch dialog correct for what your trying to do.
"ERROR: No contact with probe"
Could it be some of both going on?
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Sounds an awful lot like you have a noisy probe input.
But this says you do not have the settings in the touch dialog correct for what your trying to do.
"ERROR: No contact with probe"
Could it be some of both going on?
Thank you. A noisy input hadn't occurred to me - probably because the problem did not arise until after I upgraded from Mach3 to Mach4. None of my electronics have changed since I put them together. The wire running from board to the fitting on the case is shielded. If a noisy probe is a possible problem, any suggestions on how to fix it?
On the question of settings, I have no idea what, if anything, to change. I've attached a picture of "Touch settings" See anything set wrong?
(http://)
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It does, in fact, appear to be a noise issue. I recalled that the ESS plugin has a provision for adding noise reduction under the pins config tab. I played with it today, ramping up the amount of reduction until the fault no longer occurred. I ultimately took 5000 microseconds to correct the issue. That's just over 40% of the 12,000 allowed. Good to have it working, but I still have to figure out how to get rid of the noise. ESS says there should be no noise reduction applied to a probe. I agree.
I found that when I hooked up my VFD that there was quite a bit of noise being output. The VFD is in a separate box and wired to a separate circuit. Knowing that my grounding was all done correctly, I looked at the possibility of a noisy incoming line. I added a 30A line filter. The filter turned out to be my noise-be-gone solution.
So, I'm thinking a 120V line filter might be the solution here. Thoughts?
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Regarding noise.........
Your motion device may have a filter setting for input/s. That may be a helpful software solution. Filtering like that just makes it so the first time the signal state change is seen it won't be reported as seen. It will have to be seen as that state for some sustained period of time before it reports the state change. In other words, a quick short blip of the signal would be ignored.
The better option is to fix the noise issue through design. Sounds like you have done some for that already but shielded cable is not a guarantee and only eliminates one potential sore spot (which can actually be magnified by the shielding if not done correctly).
Keeping all low level signals in a control cabinet (away from noise) and using only 24 volts on the machine can help a lot. Using optically isolated relays to do this also gives big benefits.
Adding a capacitor to inputs has the same effect as noise filtering in software.
Adding resistors to inputs requires the input to supply more current (push harder) to change state.
A combination of caps and resistors may be an option.
This link might help too. https://www.machsupport.com/forum/index.php?topic=25616.0
Regarding touchoff settings...............
Make small increases to your retract distance and play with it to see how it affects moves. The error you got is saying the probe move finished before the probe input changed states. If the probe input never changes state while doing the actual touch move, that is the error it will report. Increasing your retract distance will increase the distance it travels in a touch move too.
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Regarding noise.........
Your motion device may have a filter setting for input/s. That may be a helpful software solution. Filtering like that just makes it so the first time the signal state change is seen it won't be reported as seen. It will have to be seen as that state for some sustained period of time before it reports the state change. In other words, a quick short blip of the signal would be ignored.
The better option is to fix the noise issue through design. Sounds like you have done some for that already but shielded cable is not a guarantee and only eliminates one potential sore spot (which can actually be magnified by the shielding if not done correctly).
Keeping all low level signals in a control cabinet (away from noise) and using only 24 volts on the machine can help a lot. Using optically isolated relays to do this also gives big benefits.
Adding a capacitor to inputs has the same effect as noise filtering in software.
Adding resistors to inputs requires the input to supply more current (push harder) to change state.
A combination of caps and resistors may be an option.
This link might help too. https://www.machsupport.com/forum/index.php?topic=25616.0
Regarding touchoff settings...............
Make small increases to your retract distance and play with it to see how it affects moves. The error you got is saying the probe move finished before the probe input changed states. If the probe input never changes state while doing the actual touch move, that is the error it will report. Increasing your retract distance will increase the distance it travels in a touch move too.
Thank you, Brett. Lot's of good information, although some of it is over my head. I'm not much of an electrical guy. I know the basic stuff - sufficient to wire a house and pass a code inspection, for example - but not too much more than that. I have a basic understanding of grounding, like star grounds, shielding, twisted pairs and such. I know that line filters work (e.g., on my VFD line), although I cannot explain why.
I'm not at my machine right now, but I'm thinking I may not have connected my drain wire to the star ground. I'll check that, and If I didn't I'll correct that and see if that takes care of the problem.
I'm still thinking about adding a line filter. Couldn't hurt. I have a question though. In researching filters, I see some rated at 120 volts, 120 volts to 250 volts and various other voltages and combinations. One model I looked at says 250 volts, but the vendor says that it's good from 0 to 250 volts. This leads me to believe that most any 250 volt filter would work on a 120 volt line. Is my thinking correct? On the recommendation of a very knowledgeable member on another forum, I purchased a TDK-Lambda RSEN 2030L (250VAC, 30A) filter for my VFD line. It worked great and cleared up the noise problem I was having. I would like to use the same filter on my 120V, 25VAC (breaker size) control line, if it will work. Will it?
Thanks again,
Gary
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Hi Gary,
electrics and electronics is my thing.
Yes a 250V 30A line filter will certainly work at 120V. It may well not be optimized for use at 120V but it will work.
Line filters are a combination of inductors and capacitors. Generally large inductors are expensive requiring many turns of
large diameter wire on a magnetic core. Manufacturers try to minimize the size of the inductance while providing a certain
level of filtering to stay cost competitive.
This works pretty well but is in fact a poor substitute for line reactors.
A line reactor is just a great big coil, 5mH or more. They are particularly useful in conjunction with VFDs.
You may have noted a quoted specification on your VFD called power factor. Without line reactors its like to be in the range
of 0.5 to 0.6. Thus if your VFD is consuming 10A only about 50% to 60% is actually going to be converted into 'real work' at the
spindle motor. Because of the switching nature of the VFD and the simple and fairly crude input circuit and filtering they are
renowned for poor power factor and 'polluting' the power supply. With a good line reactor the power factor could be 0.85 and
maybe as high as 0.95, a huge improvement, and a tenfold reduction in 'pollution' products.
A line filter will help reduce the electrical noise of a VFD to your PC for instance but it wont do squat for your power factor nor
much for an already 'polluted' power supply.
For the same money as a new line filter you could buy a second hand single phase line reactor of 5mH or so. That would be my
recommendation.
In New Zealand, especially rural New Zealand, many farmers are using 100kW level down-hole pumps (VFD controlled) for
irrigation. The power supply has become so badly polluted that in many rural areas running a PC or stereo is risky.
The power supply companies have been insisting that farmers follow the rules and fit line reactors or their electronic
equivalent. The farmers are screaming blue murder (when don't they??) about the expense, these devices approach the price
of the VFD, tens of thousands.
Craig
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Hi Gary,
electrics and electronics is my thing.
Yes a 250V 30A line filter will certainly work at 120V. It may well not be optimized for use at 120V but it will work.
Line filters are a combination of inductors and capacitors. Generally large inductors are expensive requiring many turns of
large diameter wire on a magnetic core. Manufacturers try to minimize the size of the inductance while providing a certain
level of filtering to stay cost competitive.
This works pretty well but is in fact a poor substitute for line reactors.
A line reactor is just a great big coil, 5mH or more. They are particularly useful in conjunction with VFDs.
You may have noted a quoted specification on your VFD called power factor. Without line reactors its like to be in the range
of 0.5 to 0.6. Thus if your VFD is consuming 10A only about 50% to 60% is actually going to be converted into 'real work' at the
spindle motor. Because of the switching nature of the VFD and the simple and fairly crude input circuit and filtering they are
renowned for poor power factor and 'polluting' the power supply. With a good line reactor the power factor could be 0.85 and
maybe as high as 0.95, a huge improvement, and a tenfold reduction in 'pollution' products.
A line filter will help reduce the electrical noise of a VFD to your PC for instance but it wont do squat for your power factor nor
much for an already 'polluted' power supply.
For the same money as a new line filter you could buy a second hand single phase line reactor of 5mH or so. That would be my
recommendation.
In New Zealand, especially rural New Zealand, many farmers are using 100kW level down-hole pumps (VFD controlled) for
irrigation. The power supply has become so badly polluted that in many rural areas running a PC or stereo is risky.
The power supply companies have been insisting that farmers follow the rules and fit line reactors or their electronic
equivalent. The farmers are screaming blue murder (when don't they??) about the expense, these devices approach the price
of the VFD, tens of thousands.
Craig
Hello Craig,
Very interesting information, and I understand most of it. I appreciate your writing so this no-technical guy can get useful takeaways. Thank you.
I may add a line reactor to my VFD box. Although my line filter appears to have cured the noise problems I was having (it was messing with my steppers (causing unprogrammed moves). And when I used a low tech AM radio to get a read on the noise level, the before and after change was quite remarkable. On the practical side, no more gained steps.
Is it safe to assume a line reactor would install between my line filter and the VFD vs. between the incoming line and the filter?
A quick look at Ebay here in the US disclosed a couple of new single phase line reactors. The rest listed were all 3 phase. Unless one can hook up the 2 hots on my 240V circuit (I think they call it split phase) to 2 legs on a 3 phase line reactor, it looks like it may be tough to find what I need at any price here in the US. Is it possible to use a 3 phase reactor on single phase lines?
On the 120V control box, I will try the TDK-Lambda filter first and see how it goes from there. The filter was only $21.76 USD or about $33 NZD. Inexpensive enough to give it shot. If it doesn't do the job, I'll be shopping for a reactor that will work with 240v. The single phase reactors I found Ebay appear to have two wires, one for incoming and one out. So, here in the US, they would only work with 120v. To work with 240v, a reactor would need connections for 2 in and 2 out.
Thanks again for your help.
Gary
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Hi,
Is it possible to use a 3 phase reactor on single phase lines?
Yes you can, just use one coil of the three.
Is it safe to assume a line reactor would install between my line filter and the VFD vs. between the incoming line and the filter?
The reactor goes on the line side (input supply) of the VFD. It may well be that you don't need a line filter if you use a reactor.
UNDER NO CIRCUMSTANCES do you put a filter/reactor or whatever on the output side of the VFD, that is the three phase
line between the VFD and motor UNLESS IT IS SPECIFICALLY PROVIDED FOR BY THE VFD MANUFACTURER.
The single phase reactors I found Ebay appear to have two wires, one for incoming and one out. So, here in the US, they would only work with 120v. To work with 240v, a reactor would need connections for 2 in and 2 out.
No, that is incorrect. Remember this is just a series inductance. It has an insulation rating between the coil and the iron core
but it does not have a voltage rating per se. Any well made reactor will work with a 230V input. Remember also that the
switched discontinuous current demanded by a VFD will cause large voltage excursions within the reactor and that any reactor
must withstand several times the input voltage.
May I suggest that any two wire reactor will work. Test the insulation resistance to the iron core with a Megger set to 1000V,
if it can't handle 1000V don't use it.
Craig
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Bravo! Now that's good stuff right there!
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Hi,
The single phase reactors I found Ebay appear to have two wires, one for incoming and one out. So, here in the US, they would only work with 120v. To work with 240v, a reactor would need connections for 2 in and 2 out.
No, that is incorrect. Remember this is just a series inductance. It has an insulation rating between the coil and the iron core
but it does not have a voltage rating per se. Any well made reactor will work with a 230V input. Remember also that the
switched discontinuous current demanded by a VFD will cause large voltage excursions within the reactor and that any reactor
must withstand several times the input voltage.
May I suggest that any two wire reactor will work. Test the insulation resistance to the iron core with a Megger set to 1000V,
if it can't handle 1000V don't use it.
Craig
Thank you, Craig. I guess I don't understand how to wire up a line reactor. Here is a picture of one I found on Automation Direct's website. It is a 230v single phase 12A. Looking at the photo, it looks like there are wire attachment holes for 6 pairs of wires. I cannot make sense of that, except to conclude that the reactor is designed to accommodate multiple motors. I'm not finding a diagram to see how the 2 hot wires in a U.S. split phase 240V should connect. Seems to me I need at least 2 ins and 2 outs for it to work here in the U.S. I think I understand the basic concept of series inductance (the inductance of the wire wraps in the coil), but don't understand how it figures into connecting 2 wires in our split phase 240V system.
(https://cdn.automationdirect.com/images/products/large/l_lr22p01ph.jpg)
Gary
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Hi,
looking at the photo suggests to me that there are only four wires (terminations) in use. One in and one out
for each of the two coils. Note that the iron core has two windows thus the flux from one winding will propagate through
the other two limbs, only one of which will have a coil on it. Any flux passing through that (occupied) limb will generate a voltage
in a manner identical to a transformer. As soon as any load is placed on that coil however the flux will preferentially flow though the
center limb WITHOUT a coil, ie the flux takes the path of least resistance.
What it amounts to is that you can consider the two coils to be independent of each other. Having said that there will be one
where the flux due to the current in one coil will cancel the flux from the other coil, and the net result is that it
equivalent to having NO reactor at all.
All that would be required is to reverse the current in one winding and then the full advantage of the reactor will be obtained.
Can you post a pic of the connection diagram on the top of the reactor?
I have attached a diagram of a single 230VAC supply passing through the two coils of the reactor in series.
The other diagram is two 120VAC phases feeding the 230V VFD each passing through one coil of the reactor.
Electrically they are identical, you don't need two coils for 120V dual phase operation but you can if you wish.
As I said you can hook up a coil backwards, all that happens is that they cancel each other out....no smoke or any
other histrionics. If you realize that no change has happened just reverse the terminations on one winding and your in
business.
Craig
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Thanks Craig. I think it is the connection diagram on the top of the reactor that would have cleared up at least some of my confusion. I ran across this fact sheet, but it seems pretty plain vanilla. However, it does show 2 ins and 2 outs in use. It's at the bottom of page 77. Note the sheet starts on page 71.
https://cdn.automationdirect.com/static/specs/aclr.pdf (https://cdn.automationdirect.com/static/specs/aclr.pdf)
Gary
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Just to close out this thread, I believe I have fixed the issue I was having. When I looked over the wiring inside my box, I noted that I did not connect the drain wire to ground. Rookie mistake. I cut a new piece of cable and hooked up my probe wiring as it should be. With that, the amount of noise filter went from 5000 down to 3000. So, the fix wasn't complete. I added an EMI line filter, but that did nothing at all. I considered a line reactor, but wanted to explore other things before dropping the bucks. Also, I don't have a lot of spare room inside the box, so installing a reactor would probably require major rework, or even mounting an auxiliary box. So, I kept looking for solutions.
I have a 5v power supply inside my box to power my ESS. It's the type that plugs into an normal duplex receptacle. I had my drain wire touching the PS output wire very close the body of the PS. I also had an AC power cord running a computer fan (I went with AC fans) laying to top of the wire grounding my case. For the former, I repositioned the drain wire so it was well separated from any other wiring, especially AC wiring. For the latter, which probably wasn't doing anything, I rerouted the AC wiring so it was physically separated from any grounds and DC wires.
Long story short, I am now able to use the touch menu with 0.0 noise suppression under the ESS pins tab.
Thanks all for your help.
Gary