Analog value representation
4.4 Effect on analog value representation
4.4
Effect on analog value representation
4.4.1
Influence of the supply voltage and the operating state on analog input values
The input values of the analog modules are dependent on the supply voltage for
electronics/sensors and on the operating state of the PLC (CPU of the DP master). The table
below shows this dependency.
Table 4-11
POWER ON
POWER ON
POWER OFF
4.4.2
Influence of the value range on the Analog Input 2AI RTD HF
The way electronic modules respond to analog inputs depends on where the input values fall
within the value range. This is illustrated by the table below.
Table 4-12
Response of the analog modules, depending on where the analog input value falls within the range of values
Measured value within ...
Nominal range
Over-/Undershoot range
Overflow
Underflow
Prior to parameter assignment, or
incorrect parameter assignment
30
Dependence of the analog input values on the operating state of the PLC (CPU of the
DP master) and the supply voltage L+
Operating state of the PLC
(CPU of the DP master)
RUN
STOP
-
Input value in SIMATIC S7 format
Measured value
Measured value
7FFF
H
8000
H
7FFF
H
Power supply L+ on
ET 200S (power
module)
L+ present
L+ missing
L+ present
L+ missing
L+ present
L+ missing
2AI RTD HF analog electronic module (6ES7134-4NB51-0AB0)
Input value of the electronic module with
analog inputs (evaluation possible on
the CPU of the DP master)
Process values
7FFF
until first conversion after startup,
H
or after assignment of parameters for
the module is completed.
7FFF
H
Process value
7FFF
H
-
-
Input value in SIMATIC S5 format
Measured value
Measured value
End of the overshoot range +1 plus
overflow bit
End of the underrange -1 plus overflow
bit
7FFF
H
Manual, 05/2007, A5E01076876-02