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Help With ARC-OK Waiting Issues Via CPC Port

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urbnsr
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Help With ARC-OK Waiting Issues Via CPC Port

Postby urbnsr » Sun Jul 26, 2015 5:22 pm

Hey. I'm having timing issues with my table. I have a PM85 and for the most part, the table has been running great. I did have some issues when I first got the power max, but after I installed a shielded CPC cable that I built, it was OK until earlier this week. I'm not blaming Hypertherm, but it is the cutter I have.

What I have recently is that the controller does not wait for ARC-OK before lowering to cut height and moving on. I don't notice it with 16 gauge steel at 45 amps, but now very noticeable running 65 amps while cutting 3/16" steel. 16 gauge Even though I have all shielded cables, I assumed electrical interference was causing the problem. For some reason it was ok, but not now. ??

To test interference, I turned off the Hypertherm and removed power while leaving the PM85's power switch on to possibly drain any capacitors in the unit. To my surprise, the controller acted the same way: It did not wait the 5 second setting I have for a default. If the arc-ok signal does not come up, the controller continues on. Maybe this method needs to be re-thought if this doesn't get resolved. I have this line after each M03:

M66 P0 L3 Q5 (Wait for ARC-OK from torch)

The Q5 means to wait for the signal for 5 seconds.

OK - So, while the PM85 was off, I unplugged the CPC cable from the Hypertherm and then the controller waited the 5 seconds like it is supposed to do. Plugged the cable back in and no waiting again. I thought my cable was somehow bad, so I installed the factory Hypertherm CPC cable but this won't work either: Plugged in and no wait, unplugged and waiting is fine. Controller display indicator does not indicate ARC-OK signal when the controller doesn't wait.

Thanks if you made it this far. I would appreciate any thoughts on this. The only thing I can think of is higher temperatures in the shop and higher humidity, but not sure how that can be related.

Paul

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acourtjester
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Re: Help With ARC-OK Waiting Issues Via CPC Port

Postby acourtjester » Sun Jul 26, 2015 7:28 pm

are you able to change the arc ok active signal level like to NC and opens on arc OK.
I think with the cable off it is an open signal
Why 65 amps for 3/16"
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urbnsr
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Re: Help With ARC-OK Waiting Issues Via CPC Port

Postby urbnsr » Sun Jul 26, 2015 7:52 pm

I could change to NC in the controller software setup and reverse, but wouldn't get that signal from the Hypertherm. And with the cable off, I couldn't send a signal to fire the torch.

Why not 65 amps? Speed. Time is money, I guess.

The more I think about it, I may reprogram the controller to halt feed motion unless arc-ok signal is continually high. If the arc-ok is (incorrectly) signalling ok for a millisecond way too early and then drops, no movement.

Thor
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Re: Help With ARC-OK Waiting Issues Via CPC Port

Postby Thor » Sun Jul 26, 2015 8:32 pm

I seemed to have the same problem with my PMAX85. I just put a .1 longer pierce delay than the book said and it seems fine now. Before when cutting even 18ga at book specs the control was getting Arc ok and would start to move before you could visibly see there was an arc. I don't get it but the small pierce delay fixed it for me. Though I still have a small arc volt reading with no arc fire as well, have not found the source of that yet.

urbnsr
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Re: Help With ARC-OK Waiting Issues Via CPC Port

Postby urbnsr » Sun Jul 26, 2015 9:19 pm

Interesting, Thor. You reminded me about additional pierce delay. Thanks. I think I did that a few months ago just to get through the job at the time. I may do that for now until I can program the hold motion unless the is a stable arc input. Are you able to do the same?

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Re: Help With ARC-OK Waiting Issues Via CPC Port

Postby jimcolt » Mon Jul 27, 2015 8:11 am

The arc ok (we call it arc transfer at Hypertherm) is a simple set of relay contacts that is normally open when you are not cutting metal.....when the plasma power supply senses current (amperage) through the work cable the arc transfer output relay closes, indicating the arc has transferred to the material and cutting has begun.

Your software of course must be set to monitor that input and start 1. the pierce delay timer, 2. after the pierce delay times out should index the torch down to cut height (from pierce height), and 3. Should begin x and y motion and start the arc voltage delay timer.

If these processes are not controlled by the arc transfer (arc ok) output, expect shorter consumable life, which ultimately alters cut quality.This signal is also monitored to sense loss of arc as well (low air pressure, driving the torch off the edge of the metal, anything that stops current flow through the work cable) and should immediately stop motion when a loss of arc transfer is sensed for any reason.

Jim Colt Hypertherm

urbnsr
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Re: Help With ARC-OK Waiting Issues Via CPC Port

Postby urbnsr » Mon Jul 27, 2015 9:38 am

Hi Jim. Thank you for your reply. I understand your info and agree. But the thick head, here, can't understand that at times the gcode that says wait for arc transfer for up to 5 seconds (a very long time) and either continue after transfer signal from PM85 or 5 seconds, which ever occurs first works just fine. Yesterday, there was no waiting, though. As Thor said, there is axis movement even before visually seeing an arc. I noticed this while the Hypertherm was off with no power supplied. Unplug the CPC cable and the gcode wait is respected: after 5 seconds it moves anyways. Maybe not the best was to handle it, but usually it works without errors.

This morning my no power test followed the 5 second rule with the plasma power supply off and the cable still plugged in. Only thing I notice at this point is the temps in the shop were much cooler. Still can't make that relationship connection. I should check the arc transfer input pins with an ohm meter during each time.

I am working on re-programming my controller to not move unless there is a continuous arc transfer signal present as opposed to only checking right at the m03 only. The controller was this way, but my previous cutter would hold an arc through voids in the cutting material which happens occasionally, by accident, but the controller would halt without the arc transfer signal basically ensuring a ruined part. Since the Hypertherm drops the arc under 'normal' operating setting, it makes sense to also stop movement again. This really doesn't fix the root problem, in my opinion, but it's the only thing I can think of to do to address this.

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Re: Help With ARC-OK Waiting Issues Via CPC Port

Postby waldner33 » Fri Dec 15, 2017 9:42 pm

I got a hyperterm plasma 85a on a multi cam , the plasma arcs and doesn't stop till I cancel it , it says "waiting on arc" , and after a few seconds says retry,the arc keeps going, but the plasma cutter don't move ,it never get the "arc ok signal" , and the cable from the controller to plasma is new, I'm stuck

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Re: Help With ARC-OK Waiting Issues Via CPC Port

Postby jimcolt » Mon Dec 18, 2017 11:53 am

The Arc Transfer output from Hypertherm is a mechanical relay that is normally open (pins 12 and 14 on the CPC connector). If your work cable is attached to the material being cut: 1. Torch start signal (pins 3 and 4 connected) fires the plasma torch 2. Pilot arc transfers to (work (material being cut), instantly there is current flow back to the plasma power supply through the work cable. 3. Work cable current flow means the plasma arc has transferred, is sensed by a current sensor in the power supply which signals for cutting current ramp up as well as arc transfer output relay to close. 4. Cutting machine senses relay closure and starts the pierce delay timer. 5. Once pierce delay timer finishes its time cycle (as suggested in Hyperthem cut charts) machine motion should start and torch should index from pierce height to cut height. So.....to determine if the arc transfer signal is working you need to monitor the contact closure at pins 12 and 14 when the torch is withing pierce height distance to the material, work cable is attached and the plasma torch is fired. If you do not sense contact closure then either the cable is bad or there is a bad component internally on the Hypertherm unit. If you do sense contact closure and the machine does not move after pierce delay times out...then their is an internal issue with this signal inside the cnc machine or torch height control. Jim Colt Hypertherm

waldner33
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Re: Help With ARC-OK Waiting Issues Via CPC Port

Postby waldner33 » Mon Dec 18, 2017 11:32 pm

Ok I follow what your saying , on the plasma screen it shows a pic of a tip and right after a icon with 2 arrows
, what should ground cable amp be if I put a meter over it , and voltage on 12-14 pin when firing , thanks

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Re: Help With ARC-OK Waiting Issues Via CPC Port

Postby jimcolt » Thu Dec 21, 2017 10:46 am

Any amperage on the work cable will trigger the arc transfer relay to close. If your torch fires a distance away from the material...there will be no amperage on the work cable, and no contact closure. If the torch is within the suggested pierce height distance from the material, then the arc transfers, power ramps up and the arc transfer occurs almost immediately (relay contact closes).

In regards to the cnc screens you will need to speak with MultiCam, they use their own cnc control made by XtraTech and I am not overly familiar with it. Jim Colt Hypertherm


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