The invention relates to an RS485
bus communication
time sequence control method which is characterized by comprising the following steps that: S1, a host initiates a query message, arranges and combines n slaves to be queried into a frame of message according to a serial number seq, and sends the frame of message to the slaves through a
bus; S2, the slaves receive a query message; S3, the slavesset
delay sending time tsend according to the seq serial number; S4, the slaves determine whether the
waiting time is greater than the
delay sending time tsend or not, and send a response message when the
waiting time is greater than the
delay sending time tsend; S5, the host receives a slave response message; S6, the host determines whether the current
operation time t exceeds a set value twaitor not, if so, the host ends the query, and if not, the host returns to execute the step S5. According to the method, a one-question multi-answer query mode between the host and the slaves can be realized, and the communication efficiency is greatly improved.