User Documentation

Data recorder
System manual
2696790000/02/04.2020
83
1 ... Buffer start 2 ... Number
3 ... Write position
Example
Start position: Newest sample
1 ... Buffer start 2 ... Number
3 ... Write position
The validity of a reading position is limited in the context of the buffer type
"Continuous". Upon reaching the end of the buffer, the write index breaks
down, by which existing samples are overwritten. The read functions detect
when a start position refers to samples which meanwhile have been over-
written. In this case the requested data cannot be delivered. The output pa-
rameter then contains correspondingly fewer values for actually delivered
samples. The delivered reading position for subsequent calls refers to the
current buffer state.
14.4 Recording callback from the application
For some applications, it may be sensible to combine the recording of
process variables in data recorders with process-oriented testing and/or fur-
ther processing. Over the course of each individual recording, a variable is
read only one time, but the value can be used for several actions.
For this purpose, a data indicator can be registered, which is called up at the
end of an individual recording and receives the result of the recording as ar-
guments as well as the data indicator from the registration. The recording in-
cludes the following information:
● Time stamp of the sample
● Recording position