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Feedrate Overide
« on: April 02, 2012, 12:41:58 AM »
This is my first post into the forum, so hello to you all.

I have done a full days testing now and have been unable to resolve my CNC machine moving in a jerky fashion when using feedrate over ride using the ESS.
It pulses fast and slow, and appears to have to momentarily wait for information to buffer in.
I have tested the machine with gcode that runs at 2x times speed and it moves very smoothly.
The issue is not related to the actual speed the machine is moving, it is directly related to the use of feedrate overide.

General Details are
Device -  Ethernet Smoothstepper
Driver - ESS_V10da2
Mach 3  - development versions tested - Clean installs of R3.043.059 and R3.043.060
Network interfaces - fixed IP on both the ESS and the PC Ethernet Adapter
Firewall - both on with Mach3 and configurator exceptions for private and public networks and firewall switched of for both public and private networks
Screensets - none

Mach3 config...
General Config - Read ahead from 20- 200 lines
Motor Tuning - Motor Step and Dir Pulse from 0,0  to 5,5

ESS Plug in configuration
Max Frequency - typically 1 MHz but up up to 4MHz
Max Pulse Frequency - from 256KHz down to 36Khz
I have changed these values from very high to very low with no change in the movement.
Changed the setting "Number of Data Points Mach should Pre-calculate" from default 1023 to 2046 with no effect.

Controller PC's tried
Atom Dual Core Win7x86
P4 3GHz single core with discrete graphics card Win7 x86
Swapping out controller PC's had no effect on the movement.

Ii am appealing to others who might have had some experience with an issue like this or even those who might have an educated guess.
The ESS has otherwise performed faultlessly, giving my machine nice smooth movement and an audible change in the sound of the motors moving.
If anyone can help me get my "accelerator pedal" back it would be very much appreciated.

Regards
Ross




Re: Feedrate Overide
« Reply #1 on: April 02, 2012, 07:52:14 AM »
A bit more information I did not include before.

Break Out Board - PMDX 122
All cables are high quality shielded cables
VFD is not switched on or operating during my tests.

Jeff Birt gave this good explanation of how the smoothstepper works in this SS thread elsewhere...

"The SmoothStepper plug-in takes the same moves that Mach has pre-planned and converts them into a format that is easy for the SmoothStepper to work with and feeds them out to the SS board. The SS board uses an FPGA (programmable hardware logic) to generate all the timing pulses. The SS board does buffer a limited number of moves and constantly tells the SS plug-in what it has done and where the machine is (so the machine and Mach stay in sync.) Since the SmoothStepper does all of the time critical pulse generation in hardware there is no load on the PC (the processing the SS plug-in does in minimal compared to what the parallel port driver has to do.)"

Using my limited understanding of how this all works, it seems that the communications between the SS and Mach regarding "what is done and where the machine is" is failing to achieve a real time processing speed but only when a feedrate over ride above 100% is used.

Regards
Ross
Re: Feedrate Overide
« Reply #2 on: April 02, 2012, 07:41:47 PM »
The FTP server does not seem to keep an archive the Development Versions of Mach3.
Can anyone point me to a source that will give me access to Development versions prior to .59 and .60.

Regards
Ross

Offline Hood

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Re: Feedrate Overide
« Reply #3 on: April 03, 2012, 02:52:56 AM »
Dont think development versions will help you I am afraid. I dont know why you are having the issues but I can say I use FRO via a pot on my machines and it works well. Spindle Override with a step/dir servo spindle is another matter, it is lumpy like you are describing and has been for 3 or so years. Greg is aware of this but its obviously low priority.

If you attach your xml I will have a look and see if I can find a problem in the config.
Hood
Re: Feedrate Overide
« Reply #4 on: April 03, 2012, 03:48:27 AM »
Hi Hood

Thanks for your reply and for saving me some time churning through development builds.
Attached is my mill xml file.

Regards
Ross

Offline Hood

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Re: Feedrate Overide
« Reply #5 on: April 03, 2012, 04:47:14 AM »
In the ESS config page set the max step frequency for each axis to 32KHz and see if that helps. Looking at your motor tuning the most you use is 8KHz and you have the max step frequency set to 256KHz for each axis. It may not help but is worth a try and will certainly not do any harm.
Hood
Re: Feedrate Overide
« Reply #6 on: April 03, 2012, 06:24:22 AM »
Hi Hood

I re-ran the settings with the same result.
As I have ungeared motors, even the lowest 36KHz Max Steps Frequency is going to easily cover my requirements for pulses on each axis.
Hmm resistant to a quick fix this one.... any other thoughts?

Regards
Ross

Offline Hood

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Re: Feedrate Overide
« Reply #7 on: April 03, 2012, 06:40:41 AM »
Well only other thing I can think of is I am using the first plugin for the ESS (10A) so may be worth you trying that. I use a fairly old version of Mach with the ESS as it is on the lathe and newer versions have screwed a few things up in Turn and not added any new things so no point in upgrading. I did try a newer version of the ESS plugin but it had time out issues so I quickly went back to 10a, might be worth trying.
Hood
Re: Feedrate Overide
« Reply #8 on: April 03, 2012, 06:53:25 AM »
Happy to try anything but is there some secret archive of drivers as the site is barren - very strange indeed.
A link maybe to 10a would be appreciated.

Thanks
Ross

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Re: Feedrate Overide
« Reply #9 on: April 03, 2012, 07:04:56 AM »
Have attached 10a

Hood