Rosserial between two arduinos

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Thanks for a reply. The problem is: I want to tap a serial signal from a module. I am sure the serial signal is rosserial based. I am giving this signal as an input to arduino mega. I am also running roscore at this end. But no data is received. Kindly give me suggestion if any

I have also doubt about the topic id. This topic id is transmitted serially. How come another arduino find out the name of topic from this topic id. Can you please give me some other way to tap the serial signals?

http://wiki.ros.org/rosserial/Overvie...

the setup is like this : One arduino is sending the serial signal. Another arduino is receiving the serial signal and this arduino is connected with laptop on which roscore is running. My question is how come receiving side arduino know about the topic name which sender arduino has sent?