Logging data

Logging is handled by the File Data Logger driver — it writes the values of selected variables into a binary file with the .qilog extension. The record is precise (every value with a timestamp) and compact; it can be exported to CSV at any time for further processing.

Enable logging

1. Add the FileDataLoggerDriver to the project (Home → Project Configuration → Drivers, the + button). A replay driver for later playback is prepared automatically along with it.
2. In the driver settings you can adjust:
   • file — the base of the file name (default values),
   • directory — the folder (default DataLogs next to the application),
   • append — append to an existing file (default true),
   • flushOnWrite — force a disk write after every value.
3. For each variable you want to record, check Log to FileDataLogger (the Variables section, communication detail).

📷 Image placeholder — checking Log to FileDataLogger on a variable.

How recording works

Logging runs together with the communication: it starts on Runtime → Connect and ends with Disconnect. Every start creates a new file with a timestamp in its name, e.g.:

DataLogs\values_20260709_14h32.qilog

Which variables are currently logged is shown in the Logged column of the Variable Watch window.

Next

Play the recorded data back — Replaying a log.