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@...]
>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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