ABSTRACT
The signal, which the load module of PLC mainly receives, comes from 3 parts: the flashlight door signal (manual operation), data signals of the field sensor and the state of the system running. The signals of the flashlight door mainly include the signals of the system starting, stopping, the switching of the remote control/computer control and the quick signal. The quick signal controls the direc-
1 OVERALL STRUCTURE AND WORKING PRINCIPLE OF THE SYSTEM
The system of crane intelligent control is mainly composed of industrial PC, PLC, frequency converter, wireless transmission module and different kinds of sensors. The overall structure is shown in Figure 1.
