Pilz PSSu E S 4AO U - Manual (Page 21)

Pilz GmbH & Co. KG, Felix-Wankel-Straße 2, 73760 Ostfildern, Germany
Telephone: +49 711 3409-0, Telefax: +49 711 3409-133, E-Mail: [email protected]
4-5
4.2 Configuration
4 Function description
The digital value after manufacturer scaling is calculated using the
following formula:
 y = (a
1
/ 256
D
* x) + b
1
or
 y = (a
1
/ 100
H
* x) + b
1
Key:
 y: Digital value after manufacturer scaling
 x: Digital value before manufacturer scaling
 a
1
: Gain
 b
1
: Offset
 a
1
/ 256
D
: Amplification factor
Arithmetic examples using decimal values:
The module always uses two's complement representation for internal
processing, irrespective of the configured data format. The values from
0000
H
to FFFF
H
form a number circle in the two's complement repre-
sentation. 8000
H
follows 7FFF
H
(= 32 767
D
) and is interpreted as the
lowest negative number (= -32 768
D
). 32 767
D
is never exceeded; the
value never falls below -32,768
D
.
INFORMATION
With the given amplification factor, gain (a
1
) is calculated as fol-
lows:
Gain (a
1
) = Amplification factor * 256
D
Amplification by 5 % is therefore:
1.05 * 256
D
= 269
D
Digital value
before manufacturer
scaling (x) Gain (a
1
) Offset (b
1
) Amplification factor
(a
1
/ 256
D
)
Value after
manufacturer scal-
ing (y)
1 000 256 0 1 1 000
1 000 512 0 2 2 000
1 000 32 0 0,125 125
1 000 269 500 1,05 1 550
1 000 128 -50 0,5 450
INFORMATION
If 7FFF
H
is exceeded as a result of scaling, unintended values
may be set on the output.