Using Mathematica Manipulate function to plot a transfer function - plot

Question

It's my first time asking for help here, I hope someone respond. I was hoping to post images to show the problem I had but I need at least 10 reps to do it. But I hope everyone understand what I'm asking for.
I'm trying to create a manipulate box to plot a transfer function with type in boxes so that I can type in the the transfer function and specify the x and y axis. But the plot itself is not appearing only the axis are
but if i type the code outside of "manipulate" it works.
If you try running this on Mathematica you could probably see the problem I'm having.
My mathematica code is below.
Manipulate[tfplot,
{{tfplot1, 0, "Transfer Function="}},
Delimiter,
{{fmin1, 10, "fmin = "}},
{{fmax1, 10^7, "fmax = "}},
{{ymin1, 1, "ymin = "}},
{{ymax1, 2*10^2, "ymax = "}},
Delimiter,
Row[{
Button["Plot", tfplot = LogLogPlot[Abs[tfplot2[2*Pi*I*f] /. {tfplot2[s_] -> tfplot1}], {f, fmin1, fmax1}, PlotPoints -> 1000, PlotRange -> {{fmin1, fmax1}, {ymin1, ymax1}}, PlotLabel -> "tf Plot"], ImageSize -> 80]
}]
, ControlPlacement -> {Left, Left, Left, Left, Left, Left, Left, Top}]
tfplot3 = (3.333321894500285`*^6 (4.611679331492357`*^6 - 72057.48955456808` s - 4.138291871540356`*^9 s^3 - 3.889993968666704`*^9 s^4 + s^5))/(s^2 (2.606152799059127`*^18 + 4.6278171788297256`*^16 s + 1.0779994813998577`*^14 s^2 + 1.5235290577558628`*^8 s^3 + s^4))
LogLogPlot[Abs[tfplot4[2*Pi*I*f] /. {tfplot4[s_] -> tfplot3}], {f, 10, 10^7}, PlotPoints -> 1000, PlotRange -> {{10, 10^7}, {1, 2*10^2}}, PlotLabel -> "tf Plot"]
Thank you.
Spiderfiq

Answer 1

Edit .. take 2..
Manipulate[
fplot = LogLogPlot[Abs[tfplotf /. s -> 2*Pi*I*f], {f, fmin1, fmax1},
PlotPoints -> 1000, PlotRange -> {{fmin1, fmax1}, {ymin1, ymax1}},
PlotLabel -> "tf Plot"],
{{tfplotf, (3.333321894500285`*^6 (4.611679331492357`*^6 -
72057.48955456808` s - 4.138291871540356`*^9 s^3 -
3.889993968666704`*^9 s^4 +
s^5))/(s^2 (2.606152799059127`*^18 +
4.6278171788297256`*^16 s + 1.0779994813998577`*^14 s^2 +
1.5235290577558628`*^8 s^3 + s^4))
, "Transfer Function="}},
Delimiter,
{{fmin1, 10, "fmin = "}},
{{fmax1, 10^7, "fmax = "}},
{{ymin1, 1, "ymin = "}},
{{ymax1, 2*10^2, "ymax = "}},
Delimiter,
ControlPlacement -> {Left, Left, Left, Left, Left, Left, Left, Top}]

Answer 2

This is some old code I had lying around from my System Dynamics and Controls class.
Manipulate[tf = TransferFunctionModel[eq, s];
BodePlot[tf, GridLines -> Automatic, ImageSize -> 500,
FrameLabel -> {{{"magnitude (db)", None}, {None,
"Bode plot"}}, {{"phase(deg)", None}, {"Frequency (rad/sec)",
None}}},
ScalingFunctions -> {{"Log10", "dB"}, {"Log10", "Degree"}},
PlotRange -> {{{0.1, 100}, Automatic}, {{0.1, 100},
Automatic}}], {eq, (5 s)/(s^2 + 4 s + 25)}]
-Brian