Tray,
I didn't write the Crestron module but we did write drivers for other platforms and they way you are sending the strings pretty closely matches our drivers. We are definitely sending the quotes around the command to send, as advised by ZeeVee. If I recall, once the connection for 232 is opened you can send or receive and then it get closed if you switch away, so you can maintain an rs232 connection, but they we have written it is more of a one and done type thing, much like yours.
rich
