What is a level transmitter? How to connect?

The level transmitter is the transmitter. An instrument that simply measures its height by pressure.
The measurement principle is: pressure difference = density g H, where the pressure difference can be known through the transmitter, g is known by itself, and the density is known, then H can be reversed, which is the height of the liquid level. A transmitter that uses this principle to measure liquid level is a liquid level transmitter.
A pressure transmitter is a device that converts the pressure of a gas or liquid into a usable electrical signal. The pressure transmitter can be divided into two-wire system, three-wire system and four-wire system according to the wiring method. What you see should be a four-wire pressure transmitter. Two power cables, two signal cables.
The power supply is connected to 24v direct current. The simple detection method is to use an ammeter or voltmeter to connect both ends of the signal line. After the power is connected, the ammeter will have 4ma current or the voltmeter will have 0v or 1V voltage.
Current transmitters generally have 4 wiring terminals, two of which are wired, and the other two do not need to be wired. The transmitter’s DC24V power cord is also a 4-20mA signal feedback line, that is, your secondary The AI ​​point of the meter or DAS (data acquisition system) should have a DC24V output.