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Author Topic: PWM or step and Direcrtion to control inverter drive ?  (Read 1385 times)

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PWM or step and Direcrtion to control inverter drive ?
« on: March 31, 2015, 04:16:13 AM »
Which is best ?

My Break out board supplies PWM output 0-5v

If I use this to control my Inverter drive hence my spindle speed I will need to put the PWM through a PWM to 0-10v circuit to the input of my Inverter drive.

Alternatively, I could use one of my axis drives via an off the shelf Step/Dir to 0-10v to the input of my inverter.

Any advice on which is the better method?

Additionally, my BOB has two outputs for Fwd and Rev. I'm assuming if I use the second method I would not need these ?

George
One step at a time!

Offline Hood

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Re: PWM or step and Direcrtion to control inverter drive ?
« Reply #1 on: April 07, 2015, 02:03:50 PM »
I have never used either to control a VFD so can not really say which would be best, however either one will almost certainly require the relays (Fwd/Rev) as the VFD will require these signals to let it know when to rotate and also when to change direction.
If you go with a seperate spindle controller then likely it will have the relays.

Hood
Re: PWM or step and Direcrtion to control inverter drive ?
« Reply #2 on: April 07, 2015, 04:55:35 PM »
Thanks for the reply,

I'm trashing the Chinese break out board and today I spent my Pocket Money on a Ethernet Smoothstepper with a Motion Control breakout board. ;D
I like the Break out board because the Smoothstepper sits nicely atop it.

So thanks for the advice. I'll have to wait a few days for the delivery but in the meantime I can look at my encoder disc and get that sorted.

I do believe that you mentioned in another post that only one slot is all that was needed.
Reading the Mach Lathe manual Art says 3 narrow slots and one slot 50% larger than the other 3.
If I only need one slot then the encoder disc on my spindle shaft should do as it is. It even has the original mount for the slotted opto! (picture attached)

George
One step at a time!

Offline Hood

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Re: PWM or step and Direcrtion to control inverter drive ?
« Reply #3 on: April 07, 2015, 05:28:20 PM »
You used to be able to use multi slot discs but the reality was there was very little benefit if any at all. I think Art removed that functionality a while back when he was working on the driver, not sure if it was put back or even if I am remembering correctly.


If you had been still using the PP then I would say the slot would likely have needed to be wider, the ESS however will not have an issue with that so it should work great.
Hood