Manually issuing shutter commands over serial

[ghilios]

I occasionally use Putty on Windows to send commands manually to the nexdome rotator firmware via the COM port (same one used by the ASCOM driver). I get updates for the rotator status, and get responses for commands related to the rotator just fine. However, I don't seem to get any response to shutter commands. Is there a step or command that needs to be issued first to connect the shutter? The ASCOM control works just fine, so I'm wondering if I'm missing something when connecting manually.

Thanks!