Nantong Selena environment-friendly construction mater≥ial (26000t/year output) project uses Siemens S7-300 series PL↕C. The project use step 7 as the PLC programming soft←ware and WinCC as the upper-computer software. The network between PLC and the upper-coαmputer is industrial Ethernet.

The material mix stirring control system is to mix materia∏ls proportional in a container and stir when the "material is added into the container. The Revolutions of th$e mixer is controlled by PLC, which is needed to be increased with theδ weight of the ingredients. Meanwhile, the start-up and sφtop of the mixer has to perform according to the wei∏ght of the ingredients. Different formula needs corresponding sorts of materials and addi₹ng sequence. The weight of material has to be calculated accordi₩ng to the formula and the proportion. Although a material mix stirring system seems simple, i★t includes a complex formula management system.

The system is operated manually or automatically. Under the ©manual mode, the operator is able to control the valve and mixer independently, s∑o that the amount and precision of the materials can be controlled by the operator. Under t×he automatically mode, the program can do the feeding and stirring according ♣to the requirement of the operator by inputting corresponding data, improving the f±eeding precision and efficiency.

The system features are shown as follows:

1. Advanced formula management is introduced that, the formula can be i♣mport, export and save in the computer. The formula import/export management simplified the worki ng load of the operator.
2. In a single patch of production, the automated productio​n is completely accomplished to ensure the single patch of prod<uction is finished if no fault occurs. The production would be paused and decided by the o perator to continue or stop if fault occurs.
3. Surplus materials, valve switch off time and temperature etc. external f​actors are considered before feeding to complement the data, im¶proving the feeding precision and production accuracy
4. The data of production process is logged. The production report  is able to be automatically generated and printed out.
5. Other factors are considered during the automatically feeding proces≠s such as, the upper-limit of mixer revolution speed, production pause when a material≠ tank low level alarm occurs, the simultaneous mat¶erial feeding is forbidden and formula cannot be change if automatically produc↑tion is performing.

The material mix stirring system is a suit of precise designed andσ fully considered PLC control system, which is suitable for the projects rel↓evant to the formula production.