#44 - Converting an analog signal using both TIA Portal and RSLogix5000

In this post we will convert a 4-20mA analog signal to an engineering unit in TIA Portal and RSLogix5000.

TIA Portal: The analog input is first normalized with the NORM_X instruction according to the sensor resolution, 4mA corresponds to the integer 0 and 20mA to the integer 27648. Then the normalized value is scaled with the SCALE_X instruction, where maximum and minimum values ​​are entered in engineering units.

RSLogix5000: A practical language for handling industrial processes is the Function Block Diagram (FBD). Using the Scale SCL instruction and entering the corresponding values, we obtain the same result as shown above. In addition, SCL also has the Limiting function to limit the minimum and maximum values ​​and others not shown in the image below (MaxAlarm, MinAlarm, Status, InstructFault and InRawRangeInv).

Note:

In theory, 15 bit input signal, unsigned and without diagnostic bit, is equivalent to: 2^15 - 1 = 32767