We need to convert sensor raw counts to engineering units in a PLC system.
Convert Raw Counts to Engineering Units
We have a sensor which gives a raw value input of the range 4000 to 20000. We need the sensor value in a output scaled range of 0 to 1450. Find a formula that will allow to calculate the scaled value from the raw one.
I’ll make up an example: I get a raw reading of 12456 from the sensor. How do we convert that to a scaled output value?
We have an elevated Zero (4000 = 0 Units) so you need to subtract that from the 12456 to start with. The span of your sensor 0 to 1450 units = 16000 (20000 – 4000).
Once the zero is taken care of it’s a simple percentage or ratio calculation.
((Raw Reading – 4000)/16000) x 1450 = Value
(12456 – 4000) = 8456
8456 / 16000 = 0.5285 i.e your reading is 52.85% of the 1450
0.5285 x 1450 = 766.325 units
another way to visualize it.
0% = 4000
25% = 8000
50% = 12000
75% = 16000
100% = 20000
To go from units to the raw value would be the same except you’d need to add the zero (4000) to the ratio.
What would raw value of 725 units be?
((725/1450) x 16000) + 4000
725/1450 = 0.5
0.5 x 16000 = 8000
8000 + 4000 = 12000
Hopefully now you can solve your raw counts calculations using the above formula.
Spare some time to evaluate your skills on the raw count calculations. Using the above example, find-out scaled output for the following raw counts : 15750, 35780, 6854, 24758. You can share the answers using below comments section.
Do you have any other similar formula for the conversion ? Share with us.
If you liked this article, then please subscribe to our YouTube Channel for PLC and SCADA video tutorials.