本文描述了基于西门子通讯模块CP-340 的PLC 与MAN B&M 柴油主机通讯的船舶自动监控系统设计与应用。通过西门子可编程控制器S7-300 及CP-340 通讯模块，并基于RS-422 现场总线协议对船舶柴油机的滑油压、油温、淡水压力、燃气温度等模拟量和水位、油舱高位等开关报警量进行监控，并显示在机舱控制台的各仪表和显示器上，实现了船舶机舱的自动监控。经在大中型船舶机舱中的实际应用表明，该监控系统功能完善、性能优良、可靠性高，完全能够满足船舶航行的要求标准。关键词： 船舶柴油机；PLC（S7-300）； 通讯模块（CP-340）；现场总线(RS-422）Abstract: This article described design and application of the automatic monitoring system of shipping based on communication of CP-340 module and MAN B&M diesel. According to programmable controller S7-300 and CP-340 module, analog quantities such as the oil pressure to the shipping engine, temperature of oil ,freshwater pressure, temperature of gas-fired, etc and the switch amounts such as water level, etc are controlled based on RS-422 local bus, and they are displayed on monitor. It is shown that the system with high function, good property and high reliability can meet the requirement of Shipping sails.Keywords: shipping engine；PLC；S7-300；CP-340；RS-422