Abstract: The method for transmitting messages in an elevator communication system selects a set of elevator cars from a plurality of elevator cars in the elevator system, and compares present data for the selected set of elevator cars with data stored in a single table. The present data which differs from the data stored in the table is designated as changed or differing data. This differing data is transmitted to the plurality of elevator cars. Along with the differing data, retransmission data ordered according to the priority associated therewith is also transmitted along with the differing data. In this manner, a group communication controller controls the communication for several elevator cars.

Abstract: The present invention relates to a method for transmitting messages in an elevator group control apparatus wherein a plurality of elevator controllers and a separate group controller transmit data using a covalent bus line. The invention comprises the steps of (a) transmitting, through the serial communication bus line, a data transmission period and a data transmission star point of each elevator controller, which are determined in accordance with the number of elevator cars connected with the serial communication bus line by the group controller, to the corresponding elevator controller; and (b) receiving the data transmission period and the start point which are transmitted through the serial communication line from the group controller; and (c) storing the data transmission period.