電子秤精度比較高， 但只能解決稱量系統靜態誤差， 若把電子秤與PLC 結合， 用PLC 控制給料設備的啟停和給料速度， 即可控制系統的動態精度， 達到精確稱量的目的。利用此原理， 使用S7- 300， 設計了LF 爐鐵合金微調稱量控制系統。該系統配置包括電子秤和PLC， 其電子秤由稱重傳感器和稱重變送器組成，通過PLC 的輸出控制變頻器的頻率以實現精確加料，用WinCC 完成界面設計，以S7- 300 通信模塊CP544
與連鑄機DCS 系統Net90 通訊， 在上位機VAX 上進行數據處理。
關 鍵 詞 ：PLC； 稱量控制； 電子秤
Abstract: Though electronic scales have a higher accuracy, it can only decrease static error. If
electronic scales are combined with PLC to control start and stop, and feeding speed of feeding equipment, the dynamic accuracy of the system would be controlled and the goal for precision weighing would be achieved too. According to this theory, a precision batching control system for the LF furnace is designed with PLC S7-300. The configuration of the control system includes PLC, electronic scales etc. The electronic scale consists of weighing sensor and weighing transmitters. According as the signal output of PLC, the frequency of frequency converter is controlled to realize precision feeding material. The interface is designed with WinCC, The batching control system communicates with the DCS Net90 of continuous casting machine by CP544 intelligent modular unit of S7-300, and then the data is processed in the second computer VAX.
Key Words: PLC; Control of weighing; Electronic scale