Abstract: In order to reduce the workload of the measuring personnel，the quality inspection center of Yunnan Hualian Zinc Indium Co.，Ltd. has carried out a research on the application of a variety of communication automatic control metering devices for the problem that the measuring personnel frequently run onsite to record the sampling data. The control program is written by Siemens 200 series PLC S7-200 CPU224 XP CN，and the control signals such as Mettler-Toledo IND231 weighing display，slurry divider，liquid lev⁃ el meter and pneumatic valve are displayed on the human-machine interface touch screen MT8103 IE. Bucket water（A）value，K value，real-time quality adjustment value，raw ore moisture value and cumulative tonnage value are written into the DCS control system through the program. Through the free port communication protocol，Ethernet communication protocol，MODBUS communication protocol，etc.，the automatic control of the slurry metering device is completed，and the timing record data is obtained and applied to the field data record，which improves the work efficiency and reduces the labor intensity of the staff.

Key words: PLC S7-200 CPU224XP, Mettler-Toledo IND231 weighing display instrument, pneumatic valve, communication protocol