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Rockwell Automation Publication 2080-UM002L-EN-E - November 2021
Chapter 10 Using microSD Cards
Data Log Directory Structure
The following table summarizes data logging performance on Micro800
controllers.
Data Log Function (DLG) Block
The data logging function block lets a user program to write run-time global
values into the data logging file in microSD card.
The DATALOG folder is created under the current project directory in the microSD card. In this
example, the current project directory is MYPROJECT. By default, the current project directory
name is taken from the downloaded project’s controller name or from the ConfigMeFirst.txt.
See
ConfigMeFirst.txt Configuration Settings on page 160
Subdirectories are also created following the controller RTC timestamp. This means that if RTC
date at the time of function block execution is February 02, 2019, the subfolder 2019 is created
under DATALOG. Under the 2019 folder, the subfolder 02 (which stands for the month of
February) is created. Under 02, another subfolder 02 is created, corresponding to the current
date.
Under the current working folder, the subfolder Grp01 is created. A maximum of 50 Grpxxx
folders can be generated on the microSD card per day.
Under the current Grpxxx working folder, the data log file File01.txt is created. Once this file
reaches more than 4 KB, another file, File02.txt, is automatically created to store data. The file
size is kept small in order to minimize data loss in case the card is removed or when there is
unexpected power off.
Each Grpxx folder can accommodate up to 50 files. This means that, for example, when the
Grp01 folder already stores 50 files, a new folder Grp02 is automatically created to store the
next data log files for that day. This automatic folder and file generation goes on until the
Grpxx folder reaches 50 for that day.
When a microSD card is inserted, the DLG function block looks for the last Grpxx folder and
filexx.txt file, and proceeds to do the data logging based on that information.
These data log files are
for February 2, 2019.
Data Log Specifications
Attribute
Value
Maximum datasets
10
All datasets are stored in the same file.
Maximum variables per dataset
128
Configured in Connected Components Workbench
software.
Minimum size per file
4 KB
Maximum files per Grpxx folder
(1)
(1) Once the data log limits is reached (that is, 50 Grpxx folders per day, then an error (ErrorID 3: DLG_ERR_DATAFILE_ACCESS) is
returned.
50
When directory is full, a new directory is automatically
created in RUN mode.
Maximum files (Filexx.txt) per day
50
When file reaches maximum size, a new file is
automatically created in RUN mode.
Typical data per day
10 MB
