Re: VFD control wiring question

Dave:

Sure I could do that. I'm just looking for a more elegant way that
doesn't involve more wiring around the spindle of my Bridgeport. I
figure that since there was essentially an analog tachometer
function to the VFD, this could be converted to an equivalent
digital signal (more or less the reverse to changing the pulses out
of the parallel port into an analog voltage to control the speed on
the VFD)

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Dave Fisher" <dave@d...>
wrote:

> Why not use one of the many reflective sensor systems on the

market - a foil

> strip
> is placed on the motor shaft and the drive gives a pulse out each

rev - the

> output could be fed direct to your software / system.
>
> Rgds
>
> Dave Fisher UK
>
>
> -----Original Message-----
> From: Bill Vance [mailto:ccq@x...]
> Sent: 07 March 2004 08:13
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] VFD control wiring question
>
>
> Howdy Andy, Jeff;
>
> There may be newer ones I haven't seen, but VFCs tend to operate

over a

> relatively small frequency range. You could do better with a

plain old 4046

> PLL, or perhaps one of it's newer 200+ MHz versions. Another even

wider

> range
> possibility would be to look into DLLs, (Delay Locked Loops), but

those are

> relatively new, and you find more in the way of accademic

proposals, than

> you
> do actual, "in production", chips, when web searching.
>
> Bill
>
>
> On Sat Mar 6 20:07:08 2004 Andy Wander wrote:
>
> >I would think you could do this with a Voltage-to-frequency

converter;

> check
> >out the National LM231; specs at

http://www.national.com/ds/LM/LM231.pdf

> >
> >There are other chips that could be used; I don't know if this

one is the

> >best for this application, just found it in a very quick web

search(to make

> >sure there really WERE such chips; I 'm getting' old and I'm not

as sure of

> >things as I used to be.)
> >
> >You'd need a circuit that could put out a square wave, with a

frequency

> >proportional to the voltage in. You would have to wire it up so

it put out

> >1 pulse per revolution, as I understand the Mach2 speed sensing.
> >
> >Andy Wander
> >Verrex Corporation
> >
> > -----Original Message-----
> >From: washcomp [mailto:jeff@w...]
> >Sent: Saturday, March 06, 2004 1:22 PM
> >To: CAD_CAM_EDM_DRO@yahoogroups.com
> >Subject: [CAD_CAM_EDM_DRO] VFD control wiring question
> >
> >First let me appologize - I'm posting this question to 3 groups,

so

> >if you get it more than once, please resond on whichever you like.
> >
> >I'm about to design the controls to an Omron G5+ (same as Yaskawa

and

> >a few others) VFD for my Bridgeport (1 1/2 HP). I'm using MACH2

CNC

> >software.
> >
> >There are (as in most VFD's) a bunch of contacts both in and out.
> >I think I've got the speed and direction control figured out, but

I

> >understand that contacts can be used for E-Stop and other

functions.

> >
> >Which contacts into or out of the drive do you recommend using and
> >how would you impliment them.
> >
> >Also, there is a setting to output the motor speed as analog

voltage

> >(0-10 volts D.C.). Most of the circuits I've seen convert from

PWM

> >to a voltage to control the drive. MACH2 has the ability to read

a

> >sensor delivering pulses so that it knows what speed a spindle is
> >turning. Is there an easy way to go in the other direction and
> >convert the analog voltage to pulses so that this can be emulated

and

> >fed back into MACH2 as speed (as if a rotary encoder was being

used)?

> >
> >Thanks,
> >Jeff
>
>
> --
>

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