There are many classification methods of detection and process control instruments (usually called automation instruments), which can be classified according to different principles.

For example, according to the energy used by instruments, it can be divided into pneumatic instruments, electric instruments and hydraulic instruments (rare); According to the instrument combination form, it can be divided into basic instrument, unit combination instrument and comprehensive control equipment; According to the installation form of instruments, they can be divided into field instruments, disc instruments and rack instruments. With the rapid development of microprocessors, instruments can be divided into intelligent instruments and non-intelligent instruments according to whether microprocessors are introduced or not. According to the form of instrument signal, it can be divided into analog instrument and digital instrument.

Regulating valves are classified according to their different structural characteristics and flow characteristics.

For example, the transmitter has multiple functions. Temperature transmitter can be divided into temperature detection instruments, and differential pressure transmitter can be divided into flow detection instruments.