Wow, that's a useful chart.

It's telling us that yes, for sure, the earthmate needs DTR high to work.

But you're saying that the 6v adapter setup that works for your laptop doesn't work with the empeg. Interesting. Assuming the connection to the empeg is a good connection, then you're right, it's down to software issues.

And you're sure you can communicate with the empeg at all? For instance, laptop connected to empeg via Hyperterminal at 9600bps works? (i.e., are we sure the serial port on the empeg sled is working and at the correct speed?)