This paper proposes a new CSMA/CD MAC protocol for air-conditioner control networks using only the UART built in a microcontroller as a collision detection mechanism. For performance evaluation of the proposed protocol, steady state throughput and average delay are calculated by analysis based on an imbedded Markov chain model. The analysis forecasts adequate throughput and delay for an example control network. The implementation of the proposed protocol to a very low-cost microcontroller that is installed in each air-conditioner consumed only about 1 kbytes of ROM and 20 bytes of RAM. The experiments on the performance confirmed the analysis results and obtained satisfactory throughput and average delay.

Regarding a control network for a building airconditioning system, signal waveforms on the transmission lines without terminators were calculated and compared with experiments. The calculation predicated the severe distortion in the signal waveform due to line end reflections in the cases of improper line connections such as loops or long branches.

No abstract

No abstract

No abstract