Siemens SIMATIC S5 Manual page 206

S5-115F Manual
If you want selective sampling, proceed as follows:
Set the function selector switch on the 460 AI to selective sampling.
Call FB 250 ANEI with Parameter EINZ = "1".
During coding, FB 250 ANEI will set the output parameters T Bit = "1". The result is available
when T Bit = "0".
If you want to scan the T Bit parameter, call FB 250 ANEI with EINZ = "1".
In the case of programmable controllers with the CPU 942-7UF13:
You cannot activate selective sampling on the relevant AI module as long as T BIT = 1.
Note
Assign different bits to the activity bit when different channels are called. You will
then be able to recognize which channel has been activated for coding.
FB 250 transmits a value XA within a (scaled) range defined by the user. The user defines the
desired range with the "Upper limit" (OGR) and "Lower limit" (UGR) parameters.
Scaling schematic:
Nominal range
of the module
Figure 6-1. Schematic Illustrating the Scaling of Analog Values
EWA 4NEB 811 6149-02
0GR
Scaled
range
XA
0GDR
0
UGDR
UGR
Analog value
Blocks
6-5