How can I use SISOTOOL to input systems with delays within Control System Toolbox 7.0 (R2006a)?

I want to know if SISO allows to study a transfer function including a delay.

When I execute the following commands:

h = tf(10,[1 3 10],'inputdelay',0.25);

sisotool(h)

I receive the following result

 ??? Error using ==> sisodata.loopdata.checkdata>LocalCheckModelData

 Cannot handle continuous-time models with delays.

 Use PADE to approximate the time delays.

Answer 1

[MathWorks Support Team]

This enhancement has been incorporated in Release 2009b (R2009b). For previous product releases, read below for any possible workarounds:

The ability to input systems with delays in SISOTOOL is not available within Control System Toolbox 7.0 (R2006a).

To workaround this issue, first approximate it using the PADE function.

h = tf(10,[1 3 10],'inputdelay',0.25);

hpade = pade(h,2); % approximate delay with second order pade

Then display this system using SISOTOOL:

sisotool(hpade);