Siemens SITRANS P DS III - Analog Input Function Block

Operator control functions via PROFIBUS
7.1 Communications structure for PROFIBUS PA
SITRANS P DS III with PROFIBUS PA
104 Operating Instructions, 06/2013, A5E00053276-07
7.1.5
Analog input function block
The analog input function block is part of the standard functions of transmitters. The
following figure shows the processing of the measured values up to the
output
.
M
i
Incoming measured value from the pressure transducer
block
MAN
Manual
O/S
Out of Service
OUT
Output (value, status)
AUTO
Automatic
Figure 7-5 Function groups of the analog input function block
Functional principle
The
incoming measurement value from the pressure transducer block
- or a
simulated value
prescribed through the
simulation switch
- is subject to another
normalization
(measured
value scaling) and a
projection onto the output range
through output scaling (application-
specific measured value).
Afterwards, the signal is
filtered
(damping) and check for being within preset
limit values
.
There is always an
upper and lower warning and alarm limit
available.
If the measured value has the status "Bad", the
shutdown logic
may output a
safety preset
value
: This may be the last usable measured value or a preset substitute value.
Using the
target mode
selected in the
mode and status editor
you can choose between
output of the automatically collected measured value (AUTO setting) or a manually preset
simulation value (MAN setting). If the function block is out of order (O/S setting) then the
safety preset is always output.