| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a communication device of high safety capable of connecting several electric appliances by using a communication power source of low voltage, and connecting the appliances with one another with disregard to a polarity of a communication wire. <P>SOLUTION: In this communication device for performing data communication of a serial signal among a plurality of communication units U1-Um connected with one another by means of two communication wires L1, L2 through a communication port, each of the communication units U1-Um comprises two sets of communication ports A1A2, B1B2, current loop communication circuits 20, 20' composed of series circuits of transmission elements PS2, PS4 and reception elements PS1, PS3 are formed between each pair of communication units connected by the communication wires L1, L2, and the current loop communication circuits 20, 20' are respectively provided with power source devices E, E' for communication. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
