So a small little tip when you are traveling on the high speed rail anytime between Madrid and Barcelona ... on your Renfe train ticket ... you will see an area for "CombinadoCercanias" with a 5 digit code. That can be used on your continued local train service, whether you are in Madrid or Barcelona.
The Madrid local trains are Cercanias and the Barcelona local trains are Rodiales .. but they are all part of the same Renfe train company.
At Barcelona Sants station, I went to a ticket helper (got to windows 1-5) where they help you get the Combinado ticket.
This ticket allows me to travel to my final destination, which I wanted to go to Sitges ... I simply took the local Rodiales train as shown below:
Ah, nice beach day in Sitges!
