The meaning of current output 4-20mA

Abstract: The information on the meaning of current output 4-20mA is provided by excellent flowmeter and flowmeter manufacturers. The output range of the current output type transmitter is commonly 0~20mA and 4~20mA. When the current transmitter outputs the minimum current and the maximum current, it represents the minimum and maximum rated output values ​​calibrated by the current transmitter respectively. In the following, the measurement range is taken as 0-1. More flowmeter manufacturers choose models and price quotations. You are welcome to inquire. The following is the meaning of the current output of 4-20mA. The output range of the current output type transmitter is commonly 0~20mA and 4~20mA. When the current transmitter outputs the minimum current and the maximum current, it represents the minimum and maximum rated output values ​​calibrated by the current transmitter respectively. The following is an example of a current transmitter with a measurement range of 0 to 100A. For the transmitter outputting 0-20mA, the 0mA current corresponds to the input 0A value, and the 4mA current of the transmitter outputting 4-20mA corresponds to the input 0A value. The 20mA current of the two types of sensors corresponds to the 100A value. For the transmitter outputting 0-20mA, we only need to select a suitable step-down resistor in the circuit design, and directly convert the 0-5V or 0-10V voltage on the resistor into a digital signal at the input interface of the A/D converter. Yes, circuit debugging and data processing are relatively simple. But the disadvantage is that the damage of the transmitter cannot be judged, and the open circuit and short circuit of the output of the transmitter cannot be distinguished. For a transmitter with an output of 4 to 20 mA, circuit debugging and data processing are more cumbersome. However, this kind of transmitter can judge whether the circuit is faulty and whether the transmitter is faulty by whether the current within the normal range can be detected when the transmitter circuit is blocked, short-circuited or damaged. damage, so it is more widely used. Because when the 4-20mA transmitter outputs 4mA, the voltage on the sampling resistor is not equal to 0, and the digital quantity directly converted by the analog-to-digital conversion circuit is not 0, so the single-chip microcomputer cannot be used directly, and the formula calculation is too complicated. Therefore, the general processing method is to eliminate the voltage drop generated by 4mA on the sampling resistor through the hardware circuit, and then perform A/D conversion. This kind of hardware circuit is the first to recommend RCV420, which is a precise I/V conversion circuit, as well as an I/V conversion circuit using LM258. And the sampling resistor forms a current loop, so that a 1-5V voltage drop is generated on the sampling resistor, and this voltage value is input to the 3-pin of the amplifier LM258. The resistor divider circuit is used to generate a fixed voltage value at pin 2 of the integrated circuit LM258 to offset the voltage drop generated by the 4mA current on the sampling resistor. Therefore, when the minimum value of the two-wire current transmitter is 4mA, the voltage difference between pins 3 and 2 of the LM258 is basically 0V. The LM258 and the resistor connected to it form an adjustable voltage amplifying circuit, which amplifies the voltage value of the two-wire current transmitter current on the sampling resistor and outputs it to the analog/digital conversion circuit through the 1 pin of LM258 for the single-chip CPU to read. , the 4-20mA current of the two-wire current transmitter is displayed on the LCD/LED screen in the form of 0-100A value through the data processing method. The above is the whole content of this article. You are welcome to inquire about the flowmeter selection and quotation of our factory. 'The meaning of current output 4-20mA'

Beijing Sincerity Automatic Equipment Co., Ltd thinks that a good rule of thumb to determine whether you're working on a project.

Beijing Sincerity Automatic Equipment Co., Ltd’s mission is to use our extensive mass flow meter experience to deliver tangible business results enabling our clients in industry and government to profit from the advanced use of technology. We strive to build long-term client relationships based on mutual trust and respect.

If Beijing Sincerity Automatic Equipment Co., Ltd added selling plans, offered more mass flow meter, and increased service regions, it would suit the needs of more users.