Aprilaire Communicating Thermostat, Model 8870

The Model 8870 Thermostat is field configurable to operate single and multi-stage separate heating and cooling equipment (such as furnace and air conditioner or roof top units), or single and multi-stage heat pump systems. A menu driven set up, using the message center display of the thermostat, can be used to configure many other features. Network communication is non-isolated, full duplex RS-485 (RS-422). The "A" terminals are the transmit pair while the "B" terminals are the recieve pair. This nomenclature uses the computer or host as the reference, so transmit refers to the lines on which the host transmits data to the thermostat while receive refers to the lines on which the host receives data from the thermostat. The baud rate is selectable between 9600 and 19200. Up to 64 uniquely addressed thermostats may reside on the same thermostat network.

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