Case study: storing data during long measurements? 1 Storing data in NOVA Automatic data recovery In NOVA, all the measured data points are stored in a single.nox file at the end of the measurement. The.nox file is generated in the user-defined database and it contains the measured data points as well as the procedure that was used in the experiment. The benefit of this automatic storage system is that the measurements can be performed without time delays due to reading or writing of data onto the computer hard drive. The drawback is that the data points can be lost if the computer crashes or if the power fails during the measurements. For very long measurements, it is convenient to save the data while the experiment is running. The Export ASCII data command can be used for this purpose. This command can be used to export measured data points or analysis results to a.txt file. This technical note illustrates how to use the Export ASCII data command using different practical examples on the dummy cell. 2 The Export ASCII data command The Export ASCII data command can be found in the data handling group of command (see Figure 1). Since this command is not a measurement command, it can be added anywhere in the procedure, except inside a Timed procedure command. 1 Page
NOVA Technical note 6 Figure 1 The Export ASCII data command is located in the Data handling group of commands To illustrate the use of the Export ASCII data, the Autolab Cyclic voltammetry potentiostatic procedure will be used. Several situations will be explored in this technical note, all of which can be performed on dummy cell (a). Load the Autolab Cyclic voltammetry potentiostatic procedure into the procedure editor to get started. To use the Export ASCII data command, drag and drop it at the end of the procedure (see Figure 2). 2 Page
Figure 2 Adding the Export ASCII data command to the procedure Note The symbol is shown next to the Export ASCII data command because the filename parameter is not yet linked. The Export ASCII data command has the following command parameters: Filename: provides the name and the location of the file 1. Number of columns: defines the number of columns in the file. Column delimiter: defines how data from two consecutive columns are separated from one another (Tab, space, comma, etc ). Decimal separator: defines which symbol should be used to separate the integral part of the values from the decimal part. File mode: defines how the data points should be saved in the ASCII file(s). This technical note will explore this parameter in detail. The possible settings are: Overwrite, Append and Make unique. Remarks: this remarks field can be added to the output file, for bookkeeping purposes. Write column headers: yes/no defines if the signal names should be added as headers in the ASCII file. 1 Note: the folder in which the file will be created must exist on the disk. 3 Page
NOVA Technical note 6 Column 1.. n: the parameters are linked to the values to export (n is the number of columns defined in the command). 2.1 Exporting data from a single measurement In this example, we will illustrate how to use the Export ASCII data command to export data points from a single measurement. For this purpose, first create a new folder, called Exported data, on the C:\ hard drive. Add the Export ASCII data command to the Autolab Cyclic voltammetry potentiostatic procedure as illustrated in Figure 2. In this example, the values of the Potential applied, WE(1).Current and time will be exported to a single file. Set the number of columns to three. Using the links, create a link between Column 1 in the Export ASCII data command and the Potential applied signal provided by the CV staircase command (see Figure 3). Repeat the same for the WE(1).Current signal and the Time signal. Set the column delimiter to Tab and leave the File mode unchanged (Overwrite). Figure 3 Linking the signals to the Export ASCII data command 4 Page
Next, click the button next to the Filename parameter and define a path and a filename for the output file (see Figure 4). Note The path must be valid. Figure 4 Defining the location of the output file (C:\Exported data\example 1.txt) With the three columns linked to three signals provided by the CV staircase command and the output file defined, it is possible to add a remark before starting the measurement. Click the button next to the Remarks parameter to open the Remarks editor window and add a useful comment (see Figure 5). Figure 5 Adding a remark to the output file Connect dummy cell (a) and press the start button to begin the measurement. The typical cyclic voltammetry for the dummy cell will be plotted in the measurement view. After the measurement is finished, the data will be available in the database, as usual, but an additional.txt file will be available in the C:\Exported data folder. This text file can be opened with Notepad (see Figure 6). 5 Page
NOVA Technical note 6 Figure 6 The data points recorded during the cyclic voltammetry measurement Press the Start button again. Before the measurement starts, a warning will be displayed. Since the File mode parameter is set to overwrite, the software can use the same output file again, unless the user presses the Close button during the procedure checking (see Figure 7). Figure 7 A warning is displayed during validation 6 Page
Pressing the OK button will validate the procedure and the measurement will proceed. At the end of the measurement, the data points in the Example 1.txt file will be overwritten. 2.2 Exporting data from a measurement and from data analysis As a second example, the same procedure will be used, with the addition of a data analysis command. In this example, the SG Smooth command will be used in order to smooth the data obtained during the CV staircase measurements (see Figure 8). Figure 8 Adding the SG Smooth command to the procedure The SG Smooth command can be setup in order to smooth WE(1).Current values. This requires linking of the Potential applied and WE(1).Current signals to the Input X and Input Y, respectively (see Figure 8). Add two new Export ASCII data commands at the end of the procedure and use them to create new text files (see Figure 9). 7 Page
NOVA Technical note 6 Figure 9 Adding a new Export ASCII data to the procedure Set the number of columns to two and link them to the Result X and Smoothed result Y provided by the SG Smooth command. The other parameters will be kept identical to the previous Export ASCII data command. Note To avoid confusion with the previous files, the output files have been set to C:\Exported data\example 2 data.txt and C:\Exported data\example 2 smoothed.txt, respectively. Connect dummy cell (a) and start the measurement. The typical CV staircase profile will be displayed in the measurement view. At the end of the measurement, two files will be added to the Exported data folder (see Figure 10). 8 Page
Figure 10 Two new files are added to the Exported data folder after the measurement 2.3 Exporting data from a long measurement In the third example, we will illustrate how the Export ASCII data command can be used in long measurements. Reload the Autolab Cyclic voltammetry potentiostatic procedure and add the Export ASCII data command as described in the first example (see Figure 2). Set the File mode parameter of the Export ASCII data command to Make unique and change the file name to C:\Exported data\example 3.txt (see Figure 11). 9 Page
NOVA Technical note 6 Figure 11 The procedure used in the third example (1/3) Locate the Repeat n times command in the Control group. Drag and drop this command at the very end of the procedure editor (see Figure 12). Figure 12 Adding the Repeat n times to the procedure (2/3) Using the Drag and drop method, select all the measurement commands at the top of the procedure editor and move it into the Repeat n times. Repeat the same for the Export ASCII data command. All the command should now be located inside the repeat loop as shown in Figure 13. 10 Page
Figure 13 The final procedure used in the third example (3/3) Connect dummy cell (a) and press the start button. The potentiostatic cyclic voltammetry measurement will be performed ten times in a row. At the end of each cyclic voltammogram, a.txt file will be added the to the Exported data folder (see Figure 14). The files are created while the measurement is running and writing the data to file does not interfere with the timing of the experiment. Note Figure 14 shows the contents of the Exported data folder after three repetitions. The first file is called Example 3 data.txt, the consequent files are called Example 3 data(n).txt, where n is a counter that starts at 1, automatically. 11 Page
NOVA Technical note 6 Figure 14 The exported data files are created while the measurement is running At the end of the measurement, a total of 10 unique Example 3(n).txt files should be available in the Exported data folder. 12 Page
2.4 Exporting data from a long measurement into a single file In the final example, we will illustrate how the Export ASCII data command can be used in long measurements. The same procedure as will be used but this time the File mode parameter will be set to Append. Figure 15 The final procedure used in the fourth example Change the name of the output file to Example 4 data.txt. Connect the dummy cell (a) and press the start button. At the end of each cyclic voltammogram, the recorded data points will be added to the specified ASCII file. At the end of the measurement, this file will contain all the recorded data points. 3 Conclusion Using the Export ASCII data command provides an additional safety for users performing very long experiments. Even if the power fails or if the computer crashes, the measured data points will still be available in a.txt file. Note Storage of data points into an ASCII file is performed whenever the software encounters the Export ASCII data command. 13 Page