Signal isolation (conversion) function

1. Isolate input/output signals This is the main function of a signal isolator. On the one hand, the signal isolator can solve the problem of different ground reference points when the ground loop and equipment are interconnected. On the other hand, it can effectively remove the infinite radio frequency and electromagnetic interference that the line may be subjected to during the transmission process. 2. Signal isolation and distribution In practical applications, we often encounter situations where a transmitter signal is connected to two or more receiving devices. If a series loop is used, any open circuit in the loop will cause the entire The meter on the loop has no signal, and the sum of the load resistance easily exceeds the load capacity of the transmitter, so this method is generally not used. The usual method is to connect a resistor in series in the loop, and then connect the load in parallel to the resistor to obtain a voltage signal. For example, connect a 250Ω resistor in series to convert a 4-20mA current signal into a 1-5V voltage signal. 3. Avoid power conflicts. Sometimes when field instruments are matched, due to unfavorable coordination, the following situation occurs: The signal access terminal of the receiving device (such as some DCS input card keys) has a 24V power supply (that is, the two-wire system we often call Interface), and the field is a 4-wire transmitter, and the output signal is an active signal. Therefore, the output signal of the 4-wire transmitter from the field will conflict with the two-wire power signal from the receiving device. The solution is to connect to the output loop-powered isolator, which is powered by the receiving device through the signal output line, and outputs the active signal of the field 4-wire transmitter to the receiving device after isolation, which not only avoids The power supply conflicts, and the signal is also isolated. 4. Provide power and isolate the 4-wire external power supply signal isolator, also known as the isolation distributor, which has the function of supplying power to the 2-wire transmitter, which can avoid the trouble of reconfiguring the power supply for the transmitter, and Signal isolation function is also provided. 5. Signal conversion and isolation Signal isolators generally have a signal conversion function, which can accept DC standard (or non-standard) signals, thermocouple signals, thermal resistance signals, potentiometer signals, and even AC signals, etc., and can output users Various signals needed. 6. Intelligent signal isolators With the continuous advancement of technology, many intelligent signal isolators have appeared on the market. In addition to the excellent performance of conventional signal isolators, they have added a CPU control unit and have field programmable functions ( That is, universal input type) and communication function. This kind of highly intelligent signal isolator has high application flexibility and will surely become the mainstream in this field.