Abstract: Urban rail transit works has high requirements on the informationization of shield machines. The characteristics of the application of CAN bus in the automatic control of heavyduty equipment are analyzed on basis of the application of the network technology in the control systems of shield machines. CMOS chips, such as MAX232, MAX485, LM3S2671, and PCA82C250, are used to design the physical interfaces between CAN bus and RS232 and RS485, which realizes the fullduplex communication between CAN bus and RS232 bus and RS485 bus. Multichannel A/D interfaces for data acquisition, processing and submitting are designed. The paper provides a new concept for the design of the automatic control systems of shield machines. 

Key words: shield machine control, CAN bus, serial communication, communication parameters, data acquisition