A weighing instrument is a device that displays the weight and status of an object being measured, commonly referred to as a weighing display. Initially, these instruments were analog, consisting of components such as an error amplifier, a reversible motor, a balanced bridge, an excitation power supply, a dial, and a pointer. They operated based on the principle of an automatic balance electronic potentiometer, but due to their slow speed, limited functions, and low accuracy, they have largely been replaced. Today, modern weighing displays are digital, offering greater precision and functionality. The structure of an electronic weighing instrument is complex yet efficient. One common type is illustrated in Figure 1. The digital receiver captures electrical signals from the load cell, which are typically in the form of small analog voltages (a few tens of millivolts). The circuit diagram, shown in Figure 2, includes an excitation power supply that provides operating power to the load cell and reference voltage for the A/D converter, with stability usually exceeding 0.1%. The amplification unit uses a measuring amplifier to boost the signal from the load cell, often by hundreds of times. A filtering unit then removes noise from external sources and internal amplifier interference. The A/D conversion unit transforms the analog signal into a digital one, typically using 14-bit or higher resolution. A microprocessor-based data processing unit handles tasks like data collection, calculation, and storage, sending the results through an interface. Finally, the display unit shows the weight value and status in numerical or graphical format and can communicate with external devices via various interfaces. The performance of a digital weighing instrument covers five main aspects: metrological performance, functionality, environmental adaptability, safety, and reliability. Compared to general-purpose digital scales, digital weighing instruments offer five key features: 1) a built-in sensor excitation power supply for easy use; 2) ratiometric A/D conversion and frequency multiplication technology for long-term metrological stability; 3) software that accurately simulates real-world conditions such as vibration, air balance changes, and material drop, resulting in fast, accurate, and stable readings; 4) a parameter setting unit that allows easy adjustment of settings like zero calibration, maximum capacity, and indexing, making it highly versatile; and 5) output interfaces that enable connection to various external devices, facilitating system control. According to the International Organization of Legal Metrology (OIML) Recommendation No. 3, non-automatic scales are categorized into four accuracy levels. In China, electronic weighing instruments are also divided into four grades—labeled I, II, III, and IV—each with a specific maximum allowable error, which is 0.7 times the tolerance of the corresponding class of instrument. The architecture of a scale instrument is surprisingly simple. A power supply provides energy to all components. An ADC (analog-to-digital converter) amplifies the analog signal from the sensor and converts it into a digital signal. A central processing unit, typically a microcontroller (MCU), processes this information. The processed weight signal is decoded into a readable format and displayed on the screen. Most systems include a keyboard circuit for user input, and many also feature parallel print ports, micro-drivers, RS232/RS485 interfaces for communication with host computers or other devices, and digital current loop interfaces for connecting large displays. Industrial models often include a 4–20 mA current loop interface to work with PLCs. High-end models may even have CAN bus or Ethernet interfaces. While some instruments include a USB interface, its use is limited due to short transmission distances, so it is rarely found in scale instruments. Stay tuned for more updates Tag: Electronic Weighing Instrument, Load Cell, Keyboard Circuit, Print Port, Accuracy Level Previous: After the vehicle is repaired, it is necessary to pay attention to the running-in. Next: Procedures for the use, maintenance and maintenance of the die-casting mold Eyelet and Grommet Machines,Eyelet Machines,Manual Eyelet Machine,Automatic Eyelet Machine NINGBO ZONGLAN MECHANICAL AND ELECTRICAL EQUIPMENT MANUFACTURE CO., LTD , https://www.zonglaneyelet.com