"Jim Wilkins" fired this volley in news:mq60ji$50s$1
@dont-email.me:

What does the controller expect for baud rate, parity, stop bits etc?

AND DTE/DCE control signals and/or their 'strapping'.

It's JUST RS-232. If you can't make the controller respond, the first
thing to do is put a terminal on the output of the computer, and see if
it's sending anything...

And if you don't have a terminal or another computer to use as one (with a
simple term like Hyperterm), then try a 'loopback test'.

Lloyd