help with rx3i modbus

I'm trying to get an rx3i system with a IC695CMM002 card to talk to a Moxa Io-logik module over rs485 modbus. I can get my computer to talk to it over a usb adapter, but i can't get the PLC to talk to it. I've tried setting up the other port as a modbus slave, but I can't get my computer to talk to it either. I've checked my serial settings, and they all match. I've got the data exchanges all set up. I've tried swapping the polarity of my sr485 lines. I don't have any faults in the fault table. When I send a request from the computer to the PLC with qmodmaster, I see the status light on the port flash, but qmodmaster keeps timing out. I don't think it's getting any responses back from the PLC.

Anybody else run into this kind of problem before? Are there any weird quirks i need to know about?

Can you post screen shots of the CMM002 module's configuration?
Are you triggering the configured exchanges by setting the corresponding output bits in ladder logic? What are the module's status bits telling you?