Patent ID: 8325599

Claim:
A communication system adapted in use to share a two-wire signal line with a time-division multiplexing transmission system configured to make a data transfer between a master and at least one slave by way of said two-wire signal line in accordance with a first protocol, said communication system comprising: a plurality of communication devices connected in parallel with each other to said two-wire signal line, each of said communication devices comprising: transmission signal receiving means configured to receive a transmission signal transmitted between said master and said slave in accordance with said first protocol in said time-division multiplexing system; transmitting means configured to provide a packet to be superimposed on said transmission signal and transmit said packet in accordance with a second protocol different from said first protocol, said packet including data to be transmitted to the other communication device, receiving means configured to receive said packet transmitted through said two-wire signal line from the other communication device in accordance with said second protocol; first protocol analysis means configured to analyze said transmission signal transmitted in accordance with said first protocol and received at said transmission signal receiving means to give a first protocol data transmission status; and control means configured to determine whether or not said first protocol data transmission status analyzed at said first protocol analysis means is available for transmitting said packet in accordance with said second protocol, and permit said transmitting means to transmit said packet when said status is determined to be available, wherein said control means is configured to permit said transmitting means to transmit said packet in accordance with said second protocol after a predetermined waiting time period from a rising or falling edge of said transmission signal composed of a series of pulses.