What is analog
Analog refers to some continuous change of physical quantities, such as voltage, current, pressure, speed, flow
and other semaphore, analog signal is the amplitude of continuous change with time signal, usually the voltage
signal is 0~10V, the current signal is 4~20mA, can use the PLC analog module for data acquisition, which can be
converted to digital quantity after sampling and quantization. When it comes to simulation, we have to mention AI and AO, and let’s explain AI and AO below.
07AC91-GJR5252300R0101
AI and AO’s explanation
(1) AI signal: analog input
The so-called analog quantity is 4-20mA or 0-10V current or voltage signal, input into the DCS,
after transformation, restore the original value, such as the current value displayed in the DCS; The secondary
value of the current transformer (5A) is converted into a 4-20mA signal by the current transmitter (5A corresponds
to 20mA), which is input to the DCS cabinet, and the actual current value is displayed in the DCS after conversion.
(2) AO signal: analog output
In contrast to AI, AO is the DCS output 4-20mA or 0-10V signal to control the operating parameters of the device; For
example, the speed control process of the frequency converter, taking 40HZ as an example, through remote DCS control,
that given the parameter value: 40HZ, DCS also sends a corresponding analog current value, in the range of 4-20mA (20mA
corresponds to 50HZ), the signal is passed to the controller of the frequency converter, and the frequency converter runs at 40HZ as required.