230 Rockwell Automation Publication 2080-UM002M-EN-E - April 2022
Chapter 11 Using microSD Cards
Data Log Directory Structure
The following table summarizes data logging performance on Micro800
controllers.
IMPORTANT
Data log execution time depends on the user application and its
complexity. Users are advised to data log no faster than every 2 seconds
for typical applications. Note that housekeeping takes at least 5 ms per
program scan. See Program Execution in Micro800
on page 133 for more
information on program scan and execution rules and sequence.
See also Data Log – Data Payload vs. Performance Time
on page 234.
IMPORTANT
Note that in cases where there are simultaneous RCP and DLG function
block execution or uploads/downloads/searches, the activities are
queued up and handled one by one by the program scan. You will notice a
slowdown in performance in these cases.
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 224.
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
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