Infinity Protocol Hardware

Proprietary ABCD port is really just RS485 serial(AB) and 24VAC(CD).

Port	Suggested Color	Function
A	Green	RS-485 D+
B	Yellow	RS-485 D-
C	White	24v AC Common
D	Red	24v AC Hot

Discussion of the protocol is ongoing - Join In!

	Cheap ch341/max485 based RS485 adapters like this one are known to work
	This FTDI adaptor also works and has the advantage of a ground connection, removable terminal block, and easy-to-access intermediate TTL points

Be aware of RS485 adapters may use RS232 lines to drive the transceiver mode. If this is true, disconnecting the software on the PC may drive the RS485 chip to transmit mode and stop all communication on the bus. If this happens an error will show on the thermostat, but will go away if you remove the RS485 adapter from the bus.

Serial data is 38400 8N1 and is mostly the thermostat sending requests for data and the air handler/outdoor units replying with it.

Sample Logs and simple parser - Please submit your own logs so we can compile a list of devices and registers.