Sorry Paul, this is more of a general question about the PowerFlarm circuitry.
The RS232 standard specifies both positive and negative voltage levels in the
3-15v range. This means if I want to connect my PowerFlarm to something
USB based I need an RS232-to-TTL converter. I've built this circuitry for
interfacing the PowerFlarm to my Nook/TopHat system and it works just fine.

However, in a recent conversation with another pilot he's going straight from
the DSub9 through a OTG cable to his Kobo without converting signal levels.
This means that either I don't have an accurate understanding of how his
system is wired up (most likely) or I slept in class too often while earning my
EE degree (a possibility) or the PowerFlarm circuitry can handle both USB
(TTL) and RS232 signal levels. At this point it's just a curiosity more than
anything else. Thanks for listening. :-)
- TomR