Siemens CP 1243-8 IRC Operating Instructions Manual page 83

Set limit value 'low' / Set limit value 'high'
Requirements for the function
● Configuration of the threshold trigger for this data point
● PLC tag in the bit memory operand area or data area
The analog value data point must be linked to a PLC tag in the bit memory or data area
(data block). For PLC tags of hardware modules (input operand area) limit value
configuration is not possible.
The configuration of limit values is pointless for measured values that have already been
preprocessed on the CPU.
Function
In these two input boxes, you can set a limit value in the direction of the start of the
measuring range or in the direction of the end of the measuring range. You can also
evaluate the limit values, for example as the start or end of the measuring range.
Configuration of the limit value
The limit value is configured as a whole decimal number. The range of values is based on
the range of values of the raw value of analog input modules.
Range
Overflow
Overrange
Nominal range
(unipolar / life zero)
Nominal range (bipolar)
Underrange
(unipolar / life zero)
Underrange (bipolar)
Undershoot / wire break
CP 1243-8 IRC
Operating Instructions, 06/2015, C79000-G8976-C385-01
Raw value (16 bits) of the PLC tag
Decimal Hexadecimal
32767 7FFF
32511 7EFF
...
27649 6C01
27648 6C00
...
0 0000
27648 6C00
...
0 0000
... ....
-27648 9400
-1 FFFF
...
-4864 ED00
-27649 93FF
...
-32512 8100
-32768 8000
Module output [mA]
0 .. 20
(unipolar)
> 23.515
23.515
... ...
20.001
20
... ...
0
...
-0.001
... ...
-3.518
...
< -3.518
Configuration and operation
4.7 Configuration in STEP 7 Basic
-20 .. +20 4 .. 20
(bipolar) (life zero)
> 23.515 > 22.810
23.515 22.810
... ...
20.001 20.001
20
...
4
20
...
0
...
-20
3.999
...
1.185
-20.001
...
-23.516
< 1.185
Measuring
range [%]
> 117.593
117.593
...
100.004
100
...
0
100
...
0
...
-100
-0.004
...
-17.59
-100.004
...
-117.593
< -17.593
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