Lots counting errors at using the DDCSV with MPG - DDCSV2.1 - Standalone CNC Motion Controller - Digital Dream Technology support
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Lots counting errors at using the DDCSV with MPG

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Posted at 2018-2-7 10:49:13 | All floors |Read mode
Dear Madam Dear Sirs,

I bought the DDCSV2.1 from you. And connected it with a MPG (Handwheel).

The precision was set for MPG to 0.005, if I move the handwheel
slowly or fast it gives me not a continous incrementing or decrementing
of the counters on the display.

- set precision to 0.005
- Counter incrementation on display
+0.005
+0.006
+0.005
+0.004
+0.002
+0.005
+0.005
+0.002

and not what is required, like this:
+0.005
+0.005
+0.005
+0.005
+0.005
+0.005
+0.005
+0.005

I replaced also the MPG and used also other precision.
The result is same bad, the countin is not continous.

Seems there is somewhere a bug or wrong. Please help me to
fix the error of this DDCSV2.1, else I can not use it.

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Posted at 2018-2-8 11:39:35 | All floors
Set # 448 (MPG control mode) parameter to 0 (open) to solve this problem

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Posted at 2018-2-8 12:03:35 | All floors
Under the precise control mode of mpg(#448=0), after the handwheel stops shaking, the corresponding axis still moves until all the pulses in handwheel buffer are sent;Otherwise, once the handwheel stops shaking, the corresponding axis immediately decelerates stop.

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Posted at 2018-2-24 06:56:12 | All floors
@ytliu: I could not find parameter #448 in either the version 1 or version 2 user manual!

@arco: My MPG settings are as follows:
           #428 = 1, #429 = 0, #430 = 1 (standard MPG), #431 = 0.001 (totally different to what the manual says!!), #432 = 0, #434 = 0 (not in manual)

           What are your settings and does your MPG have a standard output as opposed to UART?

Hope this helps

Will
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Posted at 2018-2-24 18:33:54 | All floors
Hello,
Parameter #448 is added in the newer version, the new version can be downloaded from http://www.ddcnc.com/forum.php?m ... &extra=page%3D1 post
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Posted at 2018-2-27 02:16:26 | All floors
Hi ytliu,

I tried your parameter settings for the #448. It does not change much or stabilize the counting. I understand that one mode is moving the motor so long i turn the wheel,
the other mode should exactly move the motor as the given value as turn by the mpg. I tried fast moving I tried slow moving, nothing changes or move the motor precise.
The digital display shows a not continous incrementing like described in the first posting.

So I measured the signals with an oscilloscope, and they are fine, no noise, no spikes, no glitches. Sadly I can not upload any pictures here from the measurement.

Kind regards
Daniel
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Posted at 2018-2-27 06:31:49 | All floors
Last edited by ytliu In 2018-2-27 08:52 Editor

Hi DAMIGO!
When turn the handwheel, if the screen coordinates only a small amount of change, the reason is generally handwheel A / B signal missing all the way caused。
Can judge the reason of the problem like this:
Disconnect handwheel B signal from controller, then turn handwheel,If the screen coordinates are still a slight change, the hand wheel A phase signal is connected to the controller B phase signal port,Then turn the handwheel, if the screen coordinates is still a slight variation, indicating the hand wheel problem, if the screen coordinates no change, indicating the controller problem.
If it is a controller fault, you can contact the dealer to replace, you can also locate and repair the fault,The figure is a schematic diagram of the handwheel coded signal.
If FPGA_WHA, FPGA_WHB signal waveforms are correct, then I'm sorry, you can only contact the vendor for replacement.
1.png
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Posted at 2018-2-27 19:30:16 | All floors
Hi ytliu,

thank you very much for your detailed explainations. I appreciate you effort to solve and to have a good product and Service.

Well this analysing I am through already. Also used 2 MPG plus a Quadrature Encoder. All of them Shows same behaviour. Please be informed my colleque Jay from the USA which have also a
DDCSV modul, has the same issues with unprecise counting. We both guess that there is a debouncer and a stable counting mechanism missing in the software.
The electronic in my humble opionion is really fine.

As Example: If am slowly turning I get Stepwidth is 0.5:

+0.5
+0.5
+0.4
+0.6
+0.5

now I turn back:
-0.5
-0.6
-0.4
-0.5
-0.5

Ist really ate the same counting back. For sure if I move very fast the MPG then it happens that's missing such counting easily and having values between 0.2-0.4.
But for now I would like to know, how this values are coming, because per tick you have to count 0.5 (given value) and to move the motor for 0.5, there can be
no way of 0.4 or 0.6 because the stepwidth is set to 0.5. So if the device would have a distortion or problem then it would miss one time 0.5 or having a 0.5 too much,
but not a value like 0.4 or 0.6.

Simulated electronic distortion:

MPG turn (tick)              Value
1                                  +0.5
1                                  +0.5
1                                  +0 or -0.5 (ooops device miss a tick or interprete the signalform wrongly)
1                                  +0.5
and so on.

   A: ___|-----|___
   B: _____|-----|____

If you respect rising and falling signal and you have a stepwidth 0.5 a counting of 2x 0.25 (rising and falling edge respected , dual Resolution)
If you respect only rising Signal and you have a counting stepwidth 0.5 a counting of 0.5 (single precision, single Resolution)

but never a range between 0.1 to 0.5 at a stepwidth of 0.5, it is just digital signal
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Posted at 2018-2-27 21:21:19 | All floors
Last edited by ytliu In 2018-2-27 21:35 Editor

Hi DAMIGO!
You said the problem should be caused by cumulative error, you can set "the pulse equivalency" to 1000 (there will be no cumulative error), and then observe the hand wheel running state.What is your current pulse equivalent setting?

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Posted at 2018-2-27 23:21:32 | All floors
DAMIGO Posted at 2018-2-27 19:30
Hi ytliu,

thank you very much for your detailed explainations.  I appreciate you effort to solve  ...

Hello DAMIGO!

I am one of the DDCSV controller technical support engineers and I am happy to respond to your questions.

You said the handwheel problem I did not reproduce here;

Can you upload the parameter picture?
I follow the parameters you set to test under.

Please upload the following parameters to me via photo or text:

[Motor Parameters]
34 X axis pulse equivalency =?
35 Y axis pulse equivalency =?
36 Z axis pulse equivalency =?
38 A axis pulse equivalency =?

[MPG parameters]
428 =?
429 =?
430 =?
431 =?
432 =?
434 =?
448 =?

Thank you!
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