Wed Oct 19 12:38:02 EDT 2011

Serial port hardware flow control

Something which has always confused me.  See wikipedia[1].

For a null modem connection which seems to be my only use case, simply
connect the RTS out of one side to the CTS in of the other and vice

/CTS input:  other side ties low to indicate it can receive more data
/RTS output: we tie low when we can receive more data.

So what about DTS / DTR?  It seems that these are connected to RTS and
CTS for a non-symmetric (non-null modem) line.

[1] http://en.wikipedia.org/wiki/RS-232_RTS/CTS#RTS.2FCTS_handshaking