Pilz PSSu E S 2AO I - Manual (Page 24)

4.2 Configuration
4 Function description
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Telephone: +49 711 3409-0, Telefax: +49 711 3409-133, E-Mail: [email protected]
4-8
4.2.3.5 Example calculation
Example calculation 4- ][Funktionsbeschreibung_BA_Konfig Skalier Bsp Aus-I
Task:
If the PIO shows a decimal value of 20 000, there should be 20 mA at the
output. User scaling should be used in this case (Gain a
2
). Manufacturer
scaling should not be changed. All numbers are decimals.
Solution:
User scaling
y = (a
2
/ 256 * x) + b
2
and manufacturer scaling
y = (a
1
/ 256 * x) + b
1
act consecutively, giving:
y = (a
1
/ 256 * ((a
2
/ 256 * x) + b
2
)) + b
1
or:
y = (a
1
* a
2
* x / 65536) + (a
1
* b
2
/ 256) + b
1
With default values for a
1
= 32, b
1
= 0 and the default value b
2
= 0:
y = a
2
* x / 2048
a
2
= y * 2048 / x
Due to the hardware calibration the converter's output range is divided
so that the 20 mA end point is assigned the value x = 4095. With the de-
fault values y = 4095 and x= 20,000 the result is:
Gain a
2
= 419