Error in Mathscript (FOPDT Transfer Function)

Hi all, i am trying to write a First Order Plus Dead Time system into the mathscript, unfortunetaly i found that it appear an error (please refer to the attachements), do anyone have idea or approach to write an FOPDT Transfer function in mathscript?
Thankyou veery much.
Solved!
Go to Solution.
Attachments:
error.png ‏18 KB

Thank you very much barp, both method work for me, but now i had face another problem.
I had try your method and design the PI controller, but the result (overshoot) is different compare to the result (overshoot) by using Matlab.
I had try to copy and paste the code from the Mathscript to the Matlab and step plot it. Consequently, the overshoot shown different value.
I also had try to check all the value and i found that everything is ok until the last line sys_cl=feedback(Gf,1), Labview has given the answer in transfer function but Matlab has show the answer in continuous time state space model.
The value of the transfer function : Gain = 58.46; Time constant = 0.55 and time delay = 0.06.
The value of Pi controller : Kp = 0.0784 and the Ti = 0.24.
I had attach some picture which show the difference.
Am i did something wrong in the mathscript and should i do it in Labview by different way?
Thankyou very much
Attachments:
matlab1.png ‏24 KB
labview bd1.png ‏28 KB
labview bd2.png ‏43 KB

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How to create a filter using mathscript transfer function in labview

Dear all,
I am currently designing a filter in labview using a Mathscript looping. The filter can be represented in transfer function. I have attachted the transfer function equation together with its value and the desire frequency vs. amplitude graph that I should obtained from it. Also, following are the transfer function written in Matlab.
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Hope to have the soonest reply from you guys. Many thanks in advance
Solved!
Go to Solution.
Attachments:
transfer function.jpg ‏18 KB
Weighting Filter.vi ‏266 KB

Thank you again for offering to help me in writing the code.
I suppose that I should do a frequency sweep on the transfer
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Weighting FilterTest1.vi ‏53 KB

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Hello,
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Solved!
Go to Solution.
Attachments:
TestPID.vi ‏31 KB

Dear Nathand,
Thanks for your answer, I tried the change and you are right. That shows that this not a standard PID, since that means (and actually I can see it now by checking inside the vi) that it is not using the derivative of the error but the derivative of the process variable. I know that this is used sometimes to prevent the effect of fast changing set-points, but it is a shame that they do not comment on it in the help, and that this is not a selectable feature. Do you know if there is a way to edit these pre-packaged vi's?
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You should be able to build control system to do this using PID control VIs. The following paper is a good place to start when working with PID systems.
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Hello,
I'm not sure that my previous message made it, so here goes again...
I am trying to implement special analog filters in Labview that are
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Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.

wrote in message news:[email protected]...
> Hello,
>
> I'm not sure that my previous message made it, so here goes again...
>
> I am trying to implement special analog filters in Labview that are
> specified by s-domain transfer functions. The only way I can think of
> to do it is to do a bilinear transformation from the s to z-domain and
> use an IIR filter. But this raises a number of other questions such as
> pre-warping frequency (is it needed, which freq. to choose)and what
> error, if any, is involved in this process.
>
> Has anyone been successful with accomplishing this through any method?
>
> Thanks in advance,
>
> David DeLoach
Hi
Do you want an off-line filter or an on-line filter? Off-line filtering
functions are available in an "advanced installation" of LV (if I remember
right) and in Signal Processing Toolset. Off-line filters handle *given*
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