Hi Adam,
I don't have your type of controller so I cannot help you specifically. Your RS232 looks a lot different than what I use on a Shadow controller (hardware handshake), for what its worth:
DB9
2 and 3 crossed
8(PCside) to 8
5 to 5+ shield
1,4,6,7 joined
DB25
2(PC side) to 2
3 to 3
7 to 5
5 to 8
Shield to 1, one end only
4,6,8,20 joined
What I'm wondering is if the controller needs hardware handshake to do DNC, as this provides a seperate signal to halt DNC, whereas software handshake requires that your controller can read XonXoff, which I understand is just a certain character (okay, I'm guessing here
) For simple program downloads/uploads, a hardware interrupt signal is not required, which is why it would still work at 9600.
In particular, note that pin 5 of a DB25 or pin 8 of a DB9 is your CTS signal, which could be critical for DNC