Instruments refer to instruments or devices used for experiments, measurement, observation, inspection and drawing in science and technology. Usually a set of equipment or machines prepared for a specific purpose. Instruments are usually used for scientific research or technical measurement, industrial automation process control, production and other purposes, generally speaking, they are special equipment or devices for a certain purpose. The instrument is a high-tech product with complex structure, which is composed of multiple parts. Instruments come in various sizes, weights and shapes, the smallest can be operated directly by hand, and the larger instruments are generally called devices or equipment.

There are mainly measuring instruments, automobile instruments, tractor instruments, navigation instruments, navigation instruments, driving instruments, radio test instruments, carrier microwave test instruments, geological exploration test instruments, building materials test instruments, seismic test instruments, geodetic instruments, hydrological instruments, timing instruments, agricultural test instruments, commercial test instruments, teaching instruments, medical instruments, environmental protection instruments and so on. ?

2. Instruments and meters belonging to mechanical industrial products include industrial automation instruments, electrical instruments and meters, optical instruments, analytical instruments, laboratory instruments and devices, material testing machines, meteorological instruments, film machinery, photographic machinery, copying micromechanics, instrument components, instrument materials, instrument process equipment, etc.

3. According to different characteristics, such as function, detection and control object, structure and principle, various instruments can be further divided into several subcategories or subcategories. For example, industrial automation instruments can be divided into detection instruments, loop display instruments, adjustment instruments and actuators according to their functions;

4. Measuring instruments are divided into temperature measuring instruments, pressure measuring instruments, flow measuring instruments, liquid level measuring instruments and mechanical measuring instruments according to the measured physical quantities. Temperature measuring instruments are divided into contact temperature measuring instruments and non-contact temperature measuring instruments according to measuring methods; Contact thermometers can be divided into thermoelectric type, expansion type and resistance type.

5. Other classification methods: The classification methods of other instruments and meters are similar, mainly related to the development process, usage habits and classification of related products. There is no uniform standard for the classification of musical instruments, and the naming of musical instruments is similar.

6. In practical work, we often divide instruments into two categories: automatic instruments and portable instruments. Automatic instrument refers to the instrument that needs to be fixed on site, also known as field-mounted instrument or dial-mounted instrument, which needs to be used with other equipment to complete one or more functions; Portable instruments are used alone, sometimes called detection instruments, and are generally divided into desktop and handheld.

7. There is also a classification of instruments, called primary instruments and secondary instruments. The primary instrument refers to the part that directly feels the measured signal, such as the sensor, and the secondary instrument refers to the part that amplifies, displays and transmits the signal.