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What does scaling mean in analog input programming?
Analog Input Scaling. What scaling means is that you convert the raw value from the analog input to some sort of engineering value. An engineering value is a number that represents the physical value e.g. flow (m3/s), weight (kg) or temperature (degrees). Converting or scaling is done simply with some math.
What do you need to know about scaling in plc?
When the analog input signal enters the PLC you will often have to scale it in your PLC program. What scaling means is that you convert the raw value from the analog input to some sort of engineering value.
How to use analog signals in PLC programming?
Many people struggle with analog signals in PLC programming. The wiring and how to use an analog input or output in your PLC program can be tricky. Most often you will see digital example PLC programs and in my Structured Text Tutorial most of the examples are digital programs.
Which is an example of an analog input module?
It is possible to buy analog input modules where you can connect a temperature sensor for example directly. But most often you will have a voltage or current input module where you connect a transmitter. Calibration is very important when talking about transmitters. You have to know how much those mA or volts represents in the physical value.
How does a voltage divider load the source signal?
The voltage divider will load the source signal. You need a divider that puts out 1/4 of the input signal. Any divider with the top resistor 3x the bottom will do that. In this case R1 = 3*R2. The impedance looking into the divider from the source will be R1+R2.
What is the resolution of an analog signal in plc?
The resolution is very important when dealing with analog signals in PLC programming. When entering the analog input card the analog signal will be split into a value between 0 and 32.767. Dividing the analog value into 32.767 gives us a certain resolution.
How many wires are needed for a 4 wire analog input?
4-wire Analog Input The 4-wire transmitter is also widely used since it separates the supply from the signal. By giving the transmitter 4 wires, you can have 2 for the supply and 2 for the signal.