Analog Value Preprocessing - Siemens S7-1200 Operating Instructions Manual

The method is explained based on the following example in which a threshold value of 2.0 is
configured.
Table 4- 3
(calculation cycle)
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.
CP 1243-7 LTE
Operating Instructions, 01/2015, C79000-G8976-C381-01
Example of the integration calculation of a threshold value configured with 2.0
Time [s] Process value
stored in the
send buffer
0 20.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5 20.5
4.0
4.5
5.0
5.5
6.0 19.9
4.15 STEP 7 configuration of individual parameters
Current process Absolute deviation
value from the stored
20.0
20.3
19.8
20.2
20.5
20.3
20.4
20.5
20.4
20.1
19.9
20.1
19.9
Configuration and operation
Integrated
deviation
value
0 0
+0.3 0.3
-0.2 0.1
+0.2 0.3
+0.5 0.8
+0.3 1.1
+0.4 1.5
+0.5 2.0
-0.1 -0.1
-0.4 -0.5
-0.6 -1.1
-0.4 -1.5
-0.6 -2.1
79