Siemens S7-1200 - Analog Value Preprocessing

Configuration and operation
4.15 STEP 7 configuration of individual parameters
CP 1243-7 LTE
Operating Instructions, 01/2015, C79000-G8976-C381-01
79
The method is explained based on the following example in which a threshold value of 2.0 is
configured.
Table 4- 3 Example of the integration calculation of a threshold value configured with 2.0
Time [s]
(calculation cycle)
Process value
stored in the
send buffer
Current process
value
Absolute deviation
from the stored
value
Integrated
deviation
0
20.0
20.0
0
0
0.5 20.3 +0.3 0.3
1.0
19.8
-0.2
0.1
1.5
20.2
+0.2
0.3
2.0
20.5
+0.5
0.8
2.5
20.3
+0.3
1.1
3.0
20.4
+0.4
1.5
3.5
20.5
20.5
+0.5
2.0
4.0
20.4
-0.1
-0.1
4.5
20.1
-0.4
-0.5
5.0
19.9
-0.6
-1.1
5.5
20.1
-0.4
-1.5
6.0
19.9
19.9
-0.6
-2.1
In this example, a value of 2.0 was configured for the threshold value trigger.
With the changes in the process value shown in the example, the threshold value trigger
fires twice, if the value 2.0 is reached:
● At the time 3.5 s: The value of the integrated deviation is at 2.0. The new process value
stored in the send buffer is 20.5.
● At the time 6.0 s: The value of the integrated deviation is at 2.1. The new process value
stored in the send buffer is 19.9.
In this example, if a deviation of the process value of approximately 0.5 should fire the
trigger, then with the behavior of the process value shown here a threshold value of
approximately 1.5 ... 2.5 would need to be configured.
4.15.7.4
Analog value preprocessing
CPs with data point configuration support analog value preprocessing with some or all of the
functions described below.