Amplifier with Geckodriver G320X

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11 Apr 2019 00:37 #130635 by twatchorn
Hi I am very new to CNC and drivers etc,

I am working on converting a wood working machine with DC servo drive motors on the X and Y axis.
I have GeckoDrive G320X DC brush servo motor drives.
The break out board is a DB25-1205F

When I test an axis in “Stepconfig” and do not have the drivers connected to the breakout board I get TTL signal at the “step” connection for X and Y ≈ 4.5v
When I connect X driver to the breakout board the signal drops to ≈ 2.2v. This is the case when driver and motor powered or not powered up. The signal at the Y step connection still stays at ≈ 4.5v.
The same thing happens when I connect the Y axis.

I have had the drivers drive the motors using a signal generator with saw-tooth wave set at 5v peak.

I have tested out a stepper motor with its driver on the bench at it has ≈ 4.5v signal and drives okay.

Am I needing an amplifier of some sort on the X & Y signals? The DB25-1205F broad does not appear to have a built in amplifier to turn on.

Any help appreciated - I am from mechanical background so please use terms that a dummy can understand!!
Thanks Trevor

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11 Apr 2019 12:35 #130658 by pl7i92
Did you stabelised the 5V 2200uF elko
dont use the USB
and also did you use the Green Board not the Blue
as well is there 12V connected to the Input Spindle Terminal

You may got a USB Fake one as so many did got in troubel

im in Europa Germany so only controled ones are sold from Trusted sellers its 12Euros not 4

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11 Apr 2019 19:57 #130692 by twatchorn
Thanks for your response, The BOB I have does not had as much on it as in the video you sent.
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12 Apr 2019 01:25 #130708 by tommylight
That is a very slow BOB, you'd be better off without it, just wire parallel port to the Geckos and be done with it.
If you still want to use it, you have to set the base thread at 100000 or it just won't work.
Have 2 of them succesfuly collecting dust somewhere is the workshop, had to use the oscilloscope to figure out what was going on with them as they did not work.

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12 Apr 2019 06:21 #130720 by pl7i92
@twatschorn

as i have been telling you you realy picked up the slowest model you can get
THIS one is for 3D printers concipated at 4steps/mm or 100steps/inch
and it will not go mutch above this numbers as lowest cost electronics
and you got a real good DRIVER hooked onto it
so
give your drivers a better Breakoutboard

IF there is a VFD Controll onbard you can be shure it is fast
but better to use a eternet card like the 7i96 to get the best out of your mashine
THE 10USD Boards work also
let me give you a idee on TB6600 as fast as it is on only 24V

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12 Apr 2019 23:04 #130744 by twatchorn
Thanks for the responses.

Yes I agree I need to buy a better BOB. The one I tried was something my son already had.
I will describe the other things I want to drive and I would appreciate suggestions on the best suited breakout board that I should get. The plan is to have a router that can also be used as a plasma cutter.
The machine I have Woodmaster Speedy 207 that someone started converting to CNC router then sold as it was not going to be big enough for their needs. It came with motors and drives but no BOB.
X and Y are the have GeckoDrive G320X DC brush servo motor drives I mentioned before.
Z is SG-30a series AC servo driver
Spindle is Bonfiglioli Vectron Frequency Inverter AGL202-i8 2 FA

These are already setup ready for connecting. I had not tried driving the Z or spindle.

We also have “LCTHC Compact digital torch module” for the plasma for installing when we get to it. Attached is it’s information sheet.

I appreciate any guidance.

This browser does not support PDFs. Please download the PDF to view it: Download PDF

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13 Apr 2019 01:18 #130748 by tommylight
Just a quick look at the pdf and it has a 10 bit ADC, encoder and a text based screen. It looks like it uses an arduino, and form the size it has to be arduino nano.
Back on topic.
Do give it a try with that BOB and set the base thread to 100000, see what speed can you attain from it and if it does not meet your expectations, try without it.
What signals does the LCTHC output ?

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13 Apr 2019 08:01 #130763 by twatchorn
Hi, Can you tell me where the base thread number is set. Is it another term for one of the settings on the "Base Information screen" in the "stepper config wizard"?
The Base period defaults to 50000 if I enter 100000.

I have found that if I have a value of 5000 or lower for the "step time" I get as good as no signal on the pam scope. A little bit of activity can be just seen with amplitude zoomed right up.
But if I have 5050 and larger values I get signal in scope. Peaks are just over 2v with the driver connected and a bit over 4v with driver disconnected from BOB.

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14 Apr 2019 00:33 #130806 by tommylight
That can be set by editing manually the ini file. Also set the step time to 15000 or you will have missed steps with that bob.

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14 Apr 2019 05:32 #130823 by twatchorn
Hi Tommy
In the ini file the word "thread" does not feature. There is "Base period" - it is already a 100,000. There is "Servo period" - it is 1,000,000.

Looked in the hal file and it has the term "base-thread", but only in the three lines below.

addf parport.0.read base-thread
addf stepgen.makepulses base-thread
addf parport.0.write base-thread

Change the step time in config to 15000. Get the same results with palmscope and motors do not drive.

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