S5-115F Manual
Analog Value Processing
Selective sampling
The 460 analog input module permits sampling of analog values
•
Cyclically
•
Selectively
In the case of cyclic sampling, the analog variables on the module are coded and buffered one
after another. The user program has no influence on coding.
In the case of selective sampling, the user program initiates coding of the desired analog variables.
Coding begins when the module is referenced.
If you want selective sampling, proceed as follows:
Set the DIP switch on the 460 AI module to selective sampling
Call FB 250 ANEI with Parameter EINZ=”1”.
During coding, FB 250 ANEI will set the output parameter 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 942-7UF11:
As long as T BIT=”1”, you must not active any further selective scanning, even on other AI 460
modules.
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 produces 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.
EWA 4NEB 811 6148-02
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