spindle with mesa 7i76e and LinuxCNC

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09 Mar 2020 15:35 #159579 by Arro
Hi everybody,

I would like to use a simple spindle for my LinuxCNC router
I see from the wiring that a VFD is connected to the TB4 (spindle) and the motor uses a 5V encoder.
Is that VFD an inverter with 10V power supply?

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09 Mar 2020 16:14 #159583 by tommylight
What do you mean by 10v power supply ?
If you are referring to the analog control input on the VFD, then almost all VFD will have a 10V output, GND, and Vref outputs/inputs on the same terminal block, and those should be wired to the Mesa spindle termial.
You can use it without encoder,
You will have to set the VFD to be controlled externally, so check the user manual.
Some VFD will also need another pin to enable the drive in CV and another for CCV if you need to reverse it. Those are usually 24V tolerant inputs or require to be brought to GND, again check manual.

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10 Mar 2020 13:36 #159652 by andypugh
The 7i76 provides a digital replacement of a potentiometer and two switches.

So, you can wire the VFD to the 7i76 exactly as the VFD manual shows wiring for a potentiometer and switches but with one very important caveat:
The switches and the potentiometer on the 7i76 are polarity sensitive and must be connected with the correct polarity.

The switches are also configured for "on" and "dir" rather than "forward" and "reverse" (ie forward = 10 and reverse = 11 rather than fwd = 10 and rev = 01)
If you can't configure the VFD to work this way then a bit of cunning may be needed. (But note that many machines have absolutely no need to reverse the spindle. Most routers, for example)

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10 Mar 2020 16:00 #159664 by Arro
I tried a quick test measuring pin 2 on TB4 (spindle output), but I have no signal (0V)
spindle-.output signal on HAL is increasing with LinuxCNC signal, 101..102..103

Referring to the Mesa Manual "Connection of Spindle" is the +10V of the VFD a digital-intput in the Mesa ?
this would be the reason coz I cannot give any voltage out

Thank Tommy and Andy for explanation !

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10 Mar 2020 16:03 - 10 Mar 2020 16:06 #159665 by MovT
Hi Arro.

The Pins on the 7i76E on TB4 are only a digital potentiometer. You need to input a voltage on a pin and then you can control the output voltage via LCNC. There is no voltage from fieldpower on TB4.

Best,
Udo
Last edit: 10 Mar 2020 16:06 by MovT.

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10 Mar 2020 16:10 #159666 by andypugh

Arro wrote: I tried a quick test measuring pin 2 on TB4 (spindle output), but I have no signal (0V)
spindle-.output signal on HAL is increasing with LinuxCNC signal, 101..102..103


It is an (isolated) digital potentiometer, it needs to be connected to the +10V and 0V of the VFD or there will be no voltage on any of the pins.

When I said "connect it like a potentiometer" I meant "connect it like the VFD manual shows a potentiometer to be connected"

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11 Mar 2020 08:23 #159762 by Arro
thanks guys, that's what I meant

was guessing the 10V coming from the represented VFD (=external)

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11 Mar 2020 08:23 - 11 Mar 2020 11:00 #159763 by Arro
thanks guys, that's what I meant

was guessing the 10V is coming from the represented VFD (=external)

and I think according the LinuxCNC parameters this 10 V is the maximum allowed
Last edit: 11 Mar 2020 11:00 by Arro. Reason: note

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