Example 1: SISO series connection
Connect three transfer functions in series
Example 2: MIMO series connection
Example 3: Series connection of two systems with 2nd output of 1st system to 1st input of 2nd system
Example 4: Series connection of two systems with 1st output of 1st system to 2nd input of 2nd system and 2nd output of 1st system to 1st input of 2nd system
Example 5: Series connection of three systems as shown in the figure.
Alternately, using the series4 result: