Learn analog input scaling methods in RSLogix 500 software using Scale with parameters (SCP) and Scale (SCL) instructions.
Analog inputs provide a way for us to understand the real-time parameters of the environment around.
Example: Temperature of the surrounding, Humidity in air, Moisture in the air, level of the water in a tank, and speed of the flow of fluids in a plant.
So all these parameters are going to be in a specific unit.
Example: level in liters, pressure in bar, the temperature in degree celsius, and etc.
But all the sensors we use to measure those parameters provide a variable voltage as output that is called Analog inputs to our Automation system.
Each sensor has a specific range of output which you can refer to the sensor manual.
Consider a sensor whose output range is 0 to 10v.
0v being the least and 10v being the maximum value of the sensor measured parameter.
But these values cannot be read into PLC as they occur. All the values that a controller reads will be in digital.
For example, an Electronic system reads the number 15 as “1111”.
In this way, Allen Bradley PLC’s read analog voltage values from 0v to 10v as 0 to 4000.
This will be the read digital value by our PLC.
0v <- – – – – – – – – -> 0
2.5v <- – – – – – – -> 1000
5v <- – – – – – – – -> 2000
7.5v <- – – – – – – -> 3000
10v <- – – – – – – – > 4000
However, we want to scale those values accurately to see exactly how much voltage the analog sensor is outputting.
Then we can use the specific unit conversion formulas to display the exact value of the parameter we are measuring.
There are two methods to scale an analog input in RSLogix 500,
In scale with parameters (SCP), there are the following specifics to be mentioned,
In scale (SCL) there are the following specifics to be mentioned,
Author: Abishek D
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