Online checkweighing has gradually become an indispensable link in the production process of modern industrial production, especially the food and pharmaceutical industries. The automatic checkweigher completes the measurement of product weight in the process of product transportation. The measured weight is compared with the preset range, and the controller issues an instruction to reject the unqualified product, or distribute products with different weight ranges to the designated area.

Automatic checkweigher usually consists of belt conveyor, controller, weighing instrument, etc. The weighing instrument completes the collection of the weight signal, and sends the weight signal to the controller for processing. The NA200 series PLC and NA-VIEW touch screen are used to upgrade the checkweigher, replacing the traditional weighing instrument and micro controller mode, which greatly reduces the cost and achieves good application results.

Hardware Configuration

Software design

The system software includes two parts: PLC program and touch screen programThe PLC program completes the experimental process in accordance with the prescribed technological requirements. NA200 series PLC compiles with scientific and reasonable logic to control the accurate and stable operation of auxiliary parts in the equipment. The control process is as follows:

1. Weighing preparation

The product enters the feed conveyor, and the speed setting of the feed conveyor is generally determined based on the distance between the products and the required speed. The purpose is to ensure that only one product is on the weighing platform during the work of the checkweigher.

2. Weighing process

After the product enters the weighing conveyor, the system recognizes that the product to be tested enters the weighing area based on external signals, such as photoelectric switch signals or internal level signals.

3. Sorting process

After the controller obtains the weight signal of the product, the system will compare it with the preset weight range and sort the products. There are mainly the following types:

• Unqualified products are rejected.
• Remove overweight and underweight separately.
• Or transported to different places according to different weight range, divided into different weight categories.

4.Report functions

Checkweigher can also provide rich report functions. Packing quantity per district, total quantity per district, qualified quantity, qualified total quantity, average value, standard deviation and total quantity and total accumulation.

Touch screen design: main interface, system settings, product settings, product statistics