Hysteresis Question

[Country Loon]

Is there a Hysteresis .vi or how can I make one up easily?

Thanks

Tom

[Bob_Y.]

What about hysteresis are you trying to find? The amount of lag a measured signal has from its source? This is easy enough to graph, and measuring it should not be too hard. I suspect that this is not what you are after, however. Could you give a few more details?

As for VIs that already do it, I have searched them and on my installation, I found only one example that used the keyword hysteresis: Basic Level Triggering of Waveforms.

I hope that this helps,
Bob Young

[Country Loon]

"Bob Y." wrote in message
news:5065000000050000007BD30100-1079395200000@exchange.ni.com...
> What about hysteresis are you trying to find? The amount of lag a
> measured signal has from its source? This is easy enough to graph,
> and measuring it should not be too hard. I suspect that this is not
> what you are after, however. Could you give a few more details?
>
> As for VIs that already do it, I have searched them and on my
> installation, I found only one example that used the keyword
> hysteresis: Basic Level Triggering of Waveforms.
>
> I hope that this helps,
> Bob Young

Ok what I have at present is an ordinary threshold ie VT where

if Vin>VT yout=1

ifVin
like a logic gate. However I would like to add hysteresis so
that when
coming from 1 back to zero the threshold changes.I suppose it is

if Vin>VT+vhys,yout=1
if Vin
I suppose this is some kind of hysteresis

[Bob_Y.]

It looks like you are probably using a loop and are asking how to get both this iteration's values and last iteration's values. The way to do this is through the use of a shift-register. Popup on the right or left edge and select "Add Shift Register". Shift registers work by moving the value from the right side this iteration to the left side next iteration. What ever you wire into it on the right, it will supply on the left next iteration.

You can (and often, but not always, should) wire something to the left from the outside of the loop for use the first iteration. This is an initialization value. You will find lots of information in the devzone about initialized shift registers and uninitialized shift registers.

Hope this helps.
Bo
b Young