Do the APPEND and CONNECT functions in the Control Systems Toolbox account for delays?

My LTI system is missing delays after I have used the APPEND and CONNECT functions to connect LTI systems together. I have combined LTI objects using the APPEND and CONNECT functions. However, the final system does not account for the delays that have been added to the LTI objects.

sys=append(K,P,G,D);

Q=[1 -2 -3 4;

    2  1 0 0;

    3  1 0 0;

    4  3 0 0];

sys2 = connect(sys,Q,2,2);

Answer 1

[MathWorks Support Team]

This bug has been fixed in Release 14 Service Pack 2 (R14SP2). For previous releases, please read below for any possible workarounds:

This is a bug in the APPEND and CONNECT functions in the way that they handle delays.

To work around this issue, you need to use the DELAY2Z function to add in the delays.

sys=delay2z(append(K,P,G,D));

Q=[1 -2 -3 4;

    2  1 0 0;

    3  1 0 0;

    4  3 0 0];

sys2 = connect(sys,Q,2,2);