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I think you forgot to advertise the topic after initlizing the node:

nh.initNode();
nh.advertise(pu);

Check tutorials: http://wiki.ros.org/rosserial_arduino/Tutorials/Hello%20World

Tip: Before trying to connect using rosserial, check if the Arduino is still running: blinking leds or something.

For formating: There's a button with zeros/ones in the top.

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