Author Topic: Running from SD card in Mach?  (Read 7935 times)

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Offline Instance

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Running from SD card in Mach?
« on: February 03, 2007, 11:35:48 AM »
I have an ncPOD running properly under Mach3.  One of the main reasons I bought a ncPOD was so that I could run G-code directly from the SD card.  I can get it to run fine from the card using the simple ncPOD VB panel.  However, I cannot find a facility to make it run from the SD card in Mach3.  Is it in there somewhere and I'm missing it? If not, any chance of adding this Art?

Offline rcrabb

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Re: Running from SD card in Mach?
« Reply #1 on: February 03, 2007, 03:37:08 PM »
I think I read a post were you would't need the SD card at all to use the pod with Mach. I don't really understand the benifit of running code from the SD card alone. Of course if you have one file you'll be running time and time again I guess I see a benifit. Can you please post more information about your situation. I am interested because I also have a pod.
« Last Edit: February 03, 2007, 03:41:31 PM by rcrabb »
Ryan

Offline Instance

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Re: Running from SD card in Mach?
« Reply #2 on: February 04, 2007, 01:57:11 AM »
Well ... I've been Mach for years, since it was Master 5 ... over several different computers and CNC's.  The main problem is that occasionally Windows background tasks cause 'skipped' steps (not missed output steps).  I've hooked a scope and frequency counter up in a count mode ... Mach never misses steps, but occasionally enough of a delay in the pulse train at the wrong time will cause a motor to skip.  This can be overcome by running your CNC slower such that the acceleration component isn't critical.  Using the ncPOD gave me *much* smoother motion.  No clunks or bangs (I use THK KR slides, so I hear anything that isn't perfect) when the hard drive light occasionally fires up from some other background task (yes, I've disabled *everything* possible).  I thought I was home free with the ncPOD.  However, in the middle of a long program I've already once experienced a problem with Mach3 and ncPOD.  I believe Mach is sending the G-codes one at a time.  While there is supposed to be some buffering on the device (per the SDK notes from OEMTECH), I've witnessed a long enough delay to cause the same time type of pulse train delay between commands while an axis is at full speed (in this case, G04's transitioning from one arc to the other).  I've loaded one of my long programs into the SD card on the ncPOD using OEMTECH's VB panel.  Heavenly -- it works perfect, smooth motion from start to finish ... never a hitch.  However, OEMTECH's VB panel is rudimentary.  It would like to use all of the features I've gotten spoiled on in Mach with the ability to run autonomously from the SD card.

Offline rcrabb

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Re: Running from SD card in Mach?
« Reply #3 on: February 04, 2007, 12:08:22 PM »
I understand completely. I have also been a Mach user from the beginning. I have not witnessed much trouble using Mach with the printer port but I have seen those "bumps" with the pod. Remember the pod plugin is not finished and I believe Art is working on gettin it to run steppers better. I'm sure in the next few days we'll see some news from Dave on the status of the pod plugin. I have been running 3 and 4 axis files with the pod and Mach3 without any "bumps". My problem was with the graphics on the screen bogging down the processor. I am very happy with the pod development so far and I'm sure they will get the last few bugs worked out. I know I really didn't answer your original question but our conversation here will trigger more responce. If there is anything I can do to help please let me know.
Ryan

Offline PeakRanger

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Re: Running from SD card in Mach?
« Reply #4 on: February 12, 2007, 04:51:01 PM »
I also bought the ncPOD hoping it would removed the "stalls" I'd seen when using Mach2 and trying to do anything else concurrently on the PC.  Ideally I'd like to run the machine and still be able to edit a CAD drawing  ;)

Initially I tried to use the ncPOD without an SD card but found that even with their control panel it wouldn't run a job.  After fitting an SD card I made better progress and although I managed to run a job, as you suggest, the control panel is still "under development".

After reading about the Mach3 / ncPOD combination I thought that the "stalls" would be banished due to USB speed overcoming the parallel port timing problems.  If the job can be downloaded prior to execution then I'd of thought the only interaction between Mach3 and ncPOD during running would be DRO updates and any stop/override functions ?

Offline Instance

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Re: Running from SD card in Mach?
« Reply #5 on: February 12, 2007, 05:07:46 PM »
I traded a couple emails with Art about this.  Apparently he is sending a stream of trajectory waypoints -- so the same problem exists as with the parallel port.  If the PC is too busy then a delay in pulse train is possible.  I also bought a ncPOD hoping it would overcome this limitation, but found the problem still exists.  FYI -- it doesn't sound like running from the SD card is in the near term roadmap for Mach.