>
> Thanks Andy, but that will probably need sent through a scale module to
> calibrate, and lacking the feedback path, will at best be a SWAG that will
> not show slowing vs loading. Adequate for surface speed calcs though.
>
That's correct, I calibrated RPM's with right gain value for scale (helped with
tachometer):
loadrt scale count=1
setp scale.0.in 0
setp scale.0.gain 0.14
setp scale.0.offset 0
addf scale.0 servo-thread
>
> His use of the C6 brings up a question in my mind as to "how is the 0-10
> volts from the C6 actually coupled into the VFD?"
My VFD has 0-10V reference input, on which I connected C6 output.
> In my lathes lashup I found that a direct connection to the pot arm
> terminal as the C6 docs show, gave an extremely non-linear control that no
> amount of faffing about with pid terms made satisfactory, but it was made
> quite linear, enough that a pid module could cope with it, by inserting a
> 10k resistor between the C6's output and the pot arm terminal of the motor
> controller. The OP might want to test that as it might improve the
> accuracy of the tach dials SWAG quite a bit. The voltage drop across that
> 10k was, in my case, only a millivolt or so, but it made a huge difference
> in the control characteristics.
>
> I might also add that the C6, if part of a feedback loop, is call a
> surveyor and set stakes slow device, so those 2 10 uf electrolytic can caps
> were replaced with .1 uf mylars in mine. One is in the analog out,
> adjacent to the terminals, the other is in the charge pump detector that
> runs the relays, time lag there is a huge problem for the motor controller
> in a mini-lathe. It sees any speed sig as an error if the relay is slow.
> His vfd may, or may not have similar don't even power up if the speed isn't
> zero logic.
>
> Just a thought. BTDT :)
>
> Cheers, Gene
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