I would start with the wire connections, You check the port with loopback wires or any port tests, What is the default baud rate? If you getting good strings back then I would look at the Transmit side of the port and loop it back to be sure it’s coming out, You have software or Hardware flow control enabled?
Xon/Xoff = Software, RTS/CTS or DTR/DSR = Hardware. Or NONE.
can you post a pic of the setup , I’m ordering an Air530 for testing but won’t have it for a few days or a week? So press on
HTH
GL 
PJ