The baud rate of 76.8k was added a loooong time ago, updating the firmware is a good bet.
For tricky communications problems like you describe you will need a tool to capture packets and study the communications flow. We use paid tools called docklight and ModbusPoll but there are many free ones out there. Modbus Poll has a limited free version.
Update: I checked with Chelsea on the ‘first line showing blank’ issue repeated below here for reference. She says to check the ‘first line’ setting in the Tstat10 advanced setup screen of T3000. There is a parameter there to select what will show on th first line of the display, in1, in10, var20, etc. Make sure its got something meaningful there.
