I recently salvaged a thermal printer saying "EM205_101122" on it's circuit board. I also got success in accessing to all it's datasheets.
It seems that it has a RS232 as well as TTL ports, but both of the ports are given two extra pins saying "RTS/DTS and DTR/DSR".
While I read about them, they are the flow control pins and are to be kept +12V or -12V.
For communication with the Arduino (as given in this tutorial: http://bildr.org/2011/08/thermal-printer-arduino/
) does these pins are required to be used or we can just use the RX TX pins only?
Help me as I'm stuck in middle of it and I just want to be sure as I don't want to burn anything trying to make it.
Ps find the datasheets as attached below