Siemens Simatic S7-400 - Manual (Page 250)

Analog Modules
5-34
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Example of Determination of the Output Error of a Module
An analog output module SM 432; AO 8 13 Bit is being used for voltage output.
The output range “
"
10 V” is used. The module is operating at an ambient
temperature of 30 ° C. The operational limit thus applies. The technical
specifications of the module state:
• Operational limit for voltage output:
"
0.5%
An output error, therefore, of
"
0.05 V (
"
0.5% of 10 V) over the whole rated range
of the module must be expected.
This means that with an actual voltage of, say, 1 V, a value in the range from 0.95
V to 1.05 V is output by the module. The relative error is
"
5% in this case.
The figure below shows for the example how the relative error becomes
increasingly less the more the output value approximates to the end of the rated
range of 10 V.
( ¢ " 0.5%*)
1 V 0 V
( ¢ " 0.625%)
Output Value
( ¢ " 5%)
8 V 10 V
* Operational limit
–1 V
"
0.05 V
" 0.05 V "
0.05 V
Figure 5-3 Example of the Relative Error of an Analog Output Module