The pictures are always below the corresponding text.
The first things to do after the program is started are in the first part of the sequence.
Here, the buttons and the input boxes for settings and starting are enabled.
The second step is to wait until the "Start" button is pressed.
After that, the data log file is opened for the first time to check if the chosen path exists. If the "file path"input box is empty or the entered value is not a path, a dialog box will appear. You can browse for a file. This prevents dialog boxes being popped up after every sample. If you change the calibration, please update the calibration date here.
Now, the input boxes and the buttons for settings and starting are disabled, the "Stop" button is enabled.
The clock is read and the reading is displayed in the "Start time" box. This box as well as the "Last measurement at" box are made visible. If you want to change the date and time format, please not that it is also used later for the "Last measurement at" time stamp and the time stamp in the log file.
In the next picture, you can see the first part of the main while loop that is stopped by pressing the "Stop" button. It includes a sequence.
Here, the values are read from the USB DAQ device. As I do not think it is important to understand to Sub-VIs, because they seem to work well, I did not try to understand them, so here is no explanation on them.
Here is the calibration formula set. If you update formulas, it might be good to keep the old values and the time of change in your notes. Then, you can update old data files if necessary. Please change the calibration date in the file header (see above).
The calibrated values are displayed in the chart and stored together with the time stamp in the log file.
The "Last measurement at" time stamp is updated.
If the "Stop" button has not been pressed, the program waits for the selected sample interval. As the program execution (readout of data, displaying and storing) takes some time a more or less precise time value is subtracted. When you compare values form station #1 and station #2, for example for calibration, it is nice to have the two loggers synchronic. Perhaps you have a better idea for this because it doesn't work very well.
If the "Stop" button if pressed, the case box is empty and the main while loop is terminated. The program will not be delayed again.
As a last step, the "Stop" button is made invisible to make it easy to see that the program is terminated.
Christian Mester, 2004-03-26