Pilz PSSu E S 2AI RTD - Manual (Page 17)

Function description
Operating Manual PSSu E S 2AI RTD(­T)
22017­EN­06 17
The ADC value is calibrated, linearised (in the case of temperature output) and scaled if
necessary.
} Raw value for sensor
The raw value of the sensor is output.
} Raw value for wire
The raw value from a feed wire is output in the case of 3­wire measurement or when a
sensor with four wires is connected. In the case of 2­wire measurement, "0" is output.
If the AD converter fails to supply a valid value, the module will adopt the last valid value for
this input instead.
4.2.6.2 Manufacturer scaling
Scaling is used to define the offset (zero point compensation) and gain (amplification) of the
digital signal. Offset and gain are entered in the system software as decimal vaues. The re­
lationship between the signal before manufacturer scaling (x), the signal after manufacturer
scaling (y), offset (b
1
) and gain (a
1
) is a linear equation as follows:
y = (a
1
/ 256
D
* x) + b
1
or
y = (a
1
/ 100
H
* x) + b
1
The term a
1
/ 256
D
corresponds to the amplification factor. With the stated amplification
factor, a
1
is calculated as follows:
a
1
= Amplification factor * 256
D
Amplification by 5 % is therefore:
1.05 * 256
D
= 269
D
Manufacturer scaling is activated in the default setting. The default value for offset is 0. The
default value for gain is 160
D
(0A0
H
). That corresponds to an amplification factor of 10/16.
The resolution is 1/10 K or 1/10 Ohm.
If the manufacturer scaling and the user scaling are deactivated, the resolution will be 1/16
K or 1/16 Ohm.
4.2.6.3 User scaling
User scaling is an additional scaling level applied after manufacturer scaling. You can use
this scaling to correct local influences. The function is the same as that of manufacturer
scaling:
} y = (a
2
/ 256
D
* x) + b
2
or
} y = (a
2
/ 100
H
* x) + b
2
} a
2
= Amplification factor * 256
D
User scaling is deactivated in the default setting. The default value for offset is 0. The de­
fault value for gain is 256
D
(100
H
). That corresponds to amplification factor 1.
If the manufacturer scaling and the user scaling are deactivated, the resolution will be 1/16
K or 1/16 Ohm.
4.2.6.4 Values that fall outside the range limits
If a value lies outside the range that can be displayed in the PII, the respective upper or
lower range limit is output (see Data formats [ 18] )