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Are there any plans to add a 0-10VDC output to control a VFD spindle drive?
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How common is this particular control scheme/ voltage? It may be possible to provide this using one of the fan/ heater outputs to provide a PWM signal and then use a fairly simple external circuit to smooth that and limit it to 0-10V
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I understand it's very common. Perhaps we should do a daughter board that plugs into the daughter board connector and the Fan2 output, to provide a 0-10V output. The FAN2 signal would provide both the 12 or 24V power we need and the PWM signal.
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In the CNC world 0-10VDC VFD spindle controls are standard. Only a few VFDs accept also a PWM input. Of course that can be solved with an external PWM to analog converter. But I prefer an integrated solution like the Azteeg X5 GT has:
http://www.panucatt.com/azteeg_X5_GT_reprap_3d_printer_controller_p/ax5gt.htm
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Ok good. In the interim a daughter board of some form would be possible.
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Awesome. I have a VFD, looking forward to somehow connecting it
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I would have a look over this thread related to GRBL - https://www.shapeoko.com/forum/viewtopic.php?f=21&t=5276 - as the solution provided there is really simple and very effective, plus it has some degree of protection. Considering that the VFD is working with relatively high voltages and it doesn't require much science to get smoke out of one, I would really avoid directly connecting the Duet to such a device.
The same board should also have provision for motor on/off and direction control, again with some isolation solution. As the VFDs usually provide 12V supply on the connectors where various controls need to be installed, better rely on that instead of using some Duet provided power.
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I did try the schematic I have indicated over a month ago and it doesn't really work! The VFD is a 1.5kW Huanyang and it works as expected, just that the board is not capable of producing the voltage, nor to change it in a rather linear manner. Amazon has several such boards readily available and for very low prices (so low that I regret spending half a day trying to sort out the problem!). I will return with comments when the one that I have ordered arrives.
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I ended up buying this module - https://www.amazon.com/gp/product/B06XZXY9M2/ref=od_aui_detailpages00?ie=UTF8&psc=1. It is cheap enough not to really bother reinventing the wheel. With my Huanyang inverter I have connected the PWM inputs to FAN 1 on the Duet, carefully configuring the jumper for 24V PWM.
On the inverter side I have shorted DCM and FOR on the upper connections bar as there is no separate spindle on/off control for now. For the 0-10V output I took +24V and DCM (digital GND) from the lower connections bar and then connected the module output to ACM (analog GND) and VI on the lower connections bar. This way there is no current flowing between the inverter and the Duet board.
For parameters - Pd001=1, Pd002=1, Pd070=0. All others are configured as for manual mode.
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@catalin_ro Thanks for the update. If you can buy a board for $10 that does not appear to be much benefit in us reinventing the wheel as you say.
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@t3p3tony Well, while it is not worth considering developing an alternative, the next Duet version could have a very simple 0-10V output (I have discovered that the analog ground used for the 0-10V input is disconnected from the digital ground in the inverter!) for the ones brave enough to directly connect it, and at least two optocouplers for spindle forward/reverse or direction/active control, with the corresponding support in firmware.
As for firmware support, the following came up:
- Separate digital spindle control lines - while I have wired the forward control line for always on, relying on the 0-10V output for actually turning on/off the spindle, normally the inverter supports a minimum spindle speed to prevent overheating. This is good to have especially for air cooled spindles.
- Calibration support for the 0-10V output. While I precisely get to 24000 RPM, when I set 5000 RPM through the M3 command I get a little bit more than 6000 RPM. While the PWM is normally precise, the conversion from PWM to voltage may be more difficult to improve.
- It would be nice to have some feedback solution from the inverter. This is a rather tricky subject as far as I could see, especially with the Chinese models. But in case the inverter has such an output, it would be nice to rely on it in order to know when the spindle has reached the target speed.
There is one better alternative to all the above - MODBUS. Smoothieboard, for example, supports this for Huanyang VFDs (http://smoothieware.org/spindle-module). All functionality can then be achieved only through simple serial commands.
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thanks! you are right having this as an option for a future board is definitely worth looking at!
