See the Dev Guide for Serial.send() and Serial.receive(). With the latter, you can pull data from the port should it be available. Note that a call to Serial.send() or Serial.match() will clear that buffer prior to send if you send anything other than an empty string or null.

If Serial.match() is not returning any data then you should also code the OnTimeout() function for the serial port because partial data will be delivered there. If OnTimeout() is missing and you are not receiving the CR (\r), the partial data is discarded. If this new callback function (OnTimeout) does not report any data, then you are likely not receiving anything and this could be due to flow control.

As clarification to a previous statement, the RFX9600 does not natively support hardware or software handshaking.

Further research into XON/XOFF yields this to be a software-based flow control scheme in which you send 2 different control characters to do flow control. These character must be embedded in your message. Personally, I've never had to muck with this but I did do a bit of googling.

Here's a link I found.

[Link: social.msdn.microsoft.com]

My personal preference would be to see if there is a way to turn XON/XOFF flow control as it would indeed make your protocol a bit easier.

FYI, Windows and Hyperterminal do this stuff for you base on COM port setup as there is a protocol/handshake layer between the COM port and the Hyperterminal program.