Device and method for full duplex RS485 bus communication based on collision-free protocol

The invention discloses a device and a method for full duplex RS485 bus communication based on collision-free protocol and belongs to the technical field of RS bus communication. The device and the method mainly solve the problem that existing RS485 buses cannot meet real-time system monitoring requirements of many monitoring nodes and huge data volume of single node uploading and are mainly characterized in that a bus data interception circuit feeds data on a sending bus back to a PLD (programmable logic device) chip, a PLD chip circuit judges occupied state of a bus and calculates data sending delay time factor through sending of bus exploring frames, if the time factor is zero, the RS485 data sending bus is grabbed to be sent, and if not, a certain time is delayed until the sending is finished. The device and the method for full duplex RS485 bus communication based on bus collision-free protocol have the advantages of realization of collision-free sending of effective data frames on the RS485 data sending bus, elimination of bus spare time on the data sending bus, effective reduction of bus collision probability of sending of the exploring frames and great improvement of utilization efficiency of the data sending bus.