The invention relates to a communication
bus, in particular to a method for automatically detecting the
cascade number of serial buses, which comprises the following steps that: a
system controller resets built-in counters, first communication ports and second communication ports of all communication nodes; the
system controller closes the reset
signal, the built-in counter starts counting, and a high-level
signal at the communication node at the
tail end of the
bus is transmitted forwards along the cascaded communication nodes; a communication node built-in counter receiving the high-level
signal stops working, and the transmission
modes of the first communication port and the second communication port are switched; after the
system controller receives the high-level signal, the built-in counters of all the communication nodes are reset; the
system controller closes the reset signal, the built-in counter starts counting, and a high-level signal sent by the communication host is reversely transmitted along the cascaded communication nodes; according to the technical scheme provided by the invention, the defects that each communication node cannot accurately and timely judge the
cascade quantity and the sorting information of the communication node in the prior art can be overcome.