Patent ID: 7684446

Claim:
A method of multiplexing analog setpoints comprising: transmitting an analog signal to a plurality of target devices on an analog communication link coupled to each of the plurality of target devices, wherein the analog signal represents multiple setpoints, each of the multiple setpoints intended for one of the plurality of target devices; transmitting a first setpoint indicator on a digital signal bus separate from the analog signal on the analog communication link to indicate to a first target device that a temperature setpoint for the first target device is being represented by the analog signal at a first time; and saving a first setpoint value asserted by the analog signal at the first target device in response to the first setpoint indicator; subsequently transmitting a target flow rate setpoint indicator to a second target device on the digital signal bus separate from the analog signal on the analog communication link to indicate to the second target device that a second setpoint is being represented by the analog signal at a second time; and saving a second setpoint value asserted by the analog signal at the second target device in response to the second setpoint indicator.