The constant-flow control in the automatic batching system employs PID regulation, while flow measurement and control combine measurement deviation with variable-frequency speed control. Based on the system’s process flow, this paper introduces the flow control methods and system control procedures of the batching system, and provides a detailed account of PLC selection as well as the hardware setup, parameter configuration, and software design processes involved in the PLC-based variable-frequency control of the batching system.

The automatic batching system is a critically important step in the production process of fine chemical plants. The quality of the batching process significantly impacts the overall quality of the final product. The automatic batching control process is a multi-input, multi-output system in which each batching and conveying line is rigorously coordinated and controlled, with precise and timely monitoring and adjustment of material levels and flow rates. The system comprises a two-level computer control network consisting of a programmable logic controller (PLC) and electronic belt scales, connected via a fieldbus to high-intelligence, high-speed devices such as field instruments, control computers, PLCs, and frequency converters. In the automatic batching production process, the main ingredients and auxiliary ingredients are combined according to specified proportions, and the electronic belt scales measure the materials conveyed by the belt conveyors. The PLC primarily handles real-time control of the conveying equipment and weighing processes, performs system fault detection, displays fault information, and generates alarms. Additionally, it sends signals to the frequency converter to adjust the belt conveyor’s speed.