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Author Topic: Mach3 + USBSmoothstepper + G540 VFD 10v output?  (Read 1272 times)

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Offline Zaae

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Mach3 + USBSmoothstepper + G540 VFD 10v output?
« on: April 24, 2017, 12:37:23 PM »
Hello again everyone :)

I have a 220v 2.2kw Huan Yang VFD. I have it successfully under the control of Mach3.

I'm using Mach3, and a USB Smoothstepper connected to a Gecko G540.

I have tested the VFD manually, and confirmed that it will reach 24000 rpm using the front panel controls.

My only problem is, the output pin for the VFD from the G540 (pin 8 ) never goes all the way to 10vdc. I have my #1 pulley configured as 12000 min, 24000 max. If I measure the voltage on this output pin, as I increase the requested rpm, the voltage gradually increases from 0v to just over 5v, but never reaches 10v. The result is, the spindle never goes above about 16000 RPM.

I have verified the ground and +10vDC on the VFD connections.

I've tried changing the VFD to use the 0-5v range instead of 0-10v, but this seems like a band-aid fix, and I'm having troubles getting the requested RPM to match the actual RPM when I tried this.

Any suggestions?

Thanks!
Z
Re: Mach3 + USBSmoothstepper + G540 VFD 10v output?
« Reply #1 on: April 24, 2017, 02:55:46 PM »
Hi,
the power supply for the USB Smoothstepper is 5V. How is it expected to produce a 0-10V output?

Either accept the 0-5V output available from the board or use external circuitry to generate the voltage you require.
One possibility is an opamp with at least a 10V supply. You could use a bit of AC trickery and make a voltage doubler.

Craig
My wife left with my best friend...
     and I miss him!

Offline Zaae

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Re: Mach3 + USBSmoothstepper + G540 VFD 10v output?
« Reply #2 on: April 24, 2017, 03:04:27 PM »
Hi Craig,

Thanks for the response.

The output pin in question is actually on the G540, not the Smoothstepper.

This is pretty much all the manual for the G540 says about it:
Code: [Select]
ANALOG OUTPUT: This is a 0V to +10V opto-isolated analog output intended for use with VFD drives. VFD OUT goes
to 0VDC while the G540 is disabled. Connect VFD GND, VFD OUT and VFD +10V to the VFD drive inputs. Make sure the
VFD drive positive voltage does not exceed +12VDC. Do not short VFD OUT to any other terminal. Do not reverse
polarity to VFD GND and VFD +10V or the G540 may be damaged.

Based on this, I expected that the output would be +10v. Maybe I should look into using an output from the Smoothstepper instead? I guess I hadn't considered that.

Thanks,
Z

Offline Tweakie.CNC

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Re: Mach3 + USBSmoothstepper + G540 VFD 10v output?
« Reply #3 on: April 25, 2017, 02:50:12 AM »
Temporarily disconnect the VFD and test the 0 - 10V analogue output from the G540. If you are unable to obtain +10V then this output from the G540 may be damaged and you should contact Gecko for their advice.

Tweakie.

edit: Because the VFD output from the G540 has isolated ground the 0 - 10 V should be taken (and measured) between terminals 7 and 9
« Last Edit: April 25, 2017, 02:55:16 AM by Tweakie.CNC »
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline Zaae

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Re: Mach3 + USBSmoothstepper + G540 VFD 10v output?
« Reply #4 on: April 26, 2017, 08:31:00 PM »
Finally figured it out. I checked the PWM signal coming out of the Smoothstepper on an oscilloscope, that looked fine. The +10v analog signal coming out of the G540 was a mess though, very noisy. The +10v reference voltage from the VFD turned out to be the culprit, a cap across the VFD's ground and output cleaned it up nicely.

Thanks for the ideas, guys.
Z