The RJ45 jack doesn't have a protocol, at least not for digital/serial communications with the thermostat, just some power pins and I/O pins for triggering control module outputs. With the TS1 we originally intended to support that kind of data acquisition and computer hookup, we used it in house for just this purpose during development, but the demand was so low for those thermostats compared to the TS2's we have phased them out of production and we never published any pin out specs or protocol specs for the TS1's serial jack. Actually, its possible we disabled serial comms on the public release TS1's, can't remember off hand.
Perhaps at some point in the future we'll reintroduce the serial comms jack and either provide software or publish a protocol spec for it. As it was, there was no data storage internally. All the serial comms did was allow computer control of the thermostat, adjustment of some parameters, and query for a data burst of the current state of the thermostat (temp, setpoint, feedrate, fan speed, etc.). For a good home user data acquisition and computer control model we'd have to store information internally and allow for periodic download and clearing of the stored data.
And if the serial jack was added back in, we would potentially be able to support user firmware updates.