Looking for details on the Duotrol HRV control system as used by many manufacturers. Has anyone seen a schematic or additional details for this controller?

In particular the Duotrol terminal board on my Honeywell HRV has a com port and a Vectouch terminal, what protocol are those and are they supported by any third party control device?

Our HRV has its own duct and damper system, pulling stale air from the bathrooms and supplying fresh air to the common area. We toggle the HRV to high speed and (further) open the corresponding damper when there is a call from a bathroom. Duotrol as supported by most manufacturers appears to have only two fixed settings, with the low constant ventilation setting roughly half the high speed setting. Altering that proportion would allow us greater on demand bathroom exhaust. And this time of year, when the house is starting to get too dry, it would allow more granularity of the constant ventilation setting as well.

It would also be nice to have some remote indication or control of when the Duotrol will call for a defrost cycle. On our HRV that defrost cycle purposely unbalances the HRV, works great, except when you are unlucky and open the door to your wood burning appliance at the same time and get a blast of combustion gases!