button or the 
button.In the Data Logger mode, the computer's clock controls measurement start/stop/interval, and readings are stored in a data log on the computer.
Note: For more efficient file management, file partitioning is used for data logs that generate large data files. The file size limit varies by bench application and is based on the number of data points, traces, and captures. If the data file size exceeds the file size limit for the bench application, BenchVue saves that file, closes it, and then opens a new file.
The default file name consists of the DMM model number followed by "Data Log" and a numeric index. For example, 34411A Data Log 31.
To change the default name, click on the existing name to open the file name editor. You can edit the prefix name and also have the option to include or exclude the date, current time, and numeric index. The date is in the form yyyy-mm-dd and the time is in the form hh-mm-ss (24-hour time format). For example, <model> Data Log 2013-09-20 11-40-26 1 – September 20, 2013 at 11:40:26 with a numeric index of 1.
Note: By default, data logs are stored in the "My Documents" folder on your computer and are organized by instrument type. For example – C:\Users\<user_name>\Documents\Keysight\BenchVue\Digital Multimeter\Data Logs\.
Immediately with Start Button - Start data logging when you click the button or the button.
At Specific Time - Start data logging at a specific time and date. Enter the desired date in the form yyyy (year), mm (month), and dd (day). Enter the desired time in the form hh (hours), mm (minutes), and ss (seconds).
On External Trigger - Trigger on a negative-going (falling) edge of an external signal on the DMM's Ext Trig connector (external triggering is not supported on the 34401A DMM).
Enter the desired interval between samples in the form dd (days), hh (hours), mm (minutes), ss (seconds), and ms (milliseconds). Select Minimum to select the shortest interval based on the instrument's current settings.
Immediately with Stop Button - Terminate data logging when you click the 
button or the 
button.
After Elapsed Time - Terminate data logging after the specified amount of time has elapsed. Enter the desired duration in the form dd (days), hh (hours), mm (minutes), and ss (seconds).
After Number of Samples Acquired - Terminate data logging after a specific number of samples have been taken.
Check readings against upper and lower limits. A limit failure occurs when the measured signal goes above the upper limit, or below the lower limit.
Enable Limit Testing - Check here to enable limit testing.
Upper Limit - Specify the upper limit in the units of the selected measurement (must be greater than the lower limit). You can also use limit markers as described below.
Lower Limit - Specify the lower limit in the units of the selected measurement (must be less than the upper limit). You can also use limit markers as described below.
Limit Markers - When limit testing is enabled, the upper and lower limits are shown on the graph with a horizontal dashed orange line (click here to see an example). To position the markers, drag the marker lines up or down on the graph. The upper limit marker must be positioned above the lower limit marker.
Send Computer Beep - The PC and the instrument beep on each limit failure.
Send E-mail Message - Sends an e-mail to the specified recipient upon the first limit failure (multiple failures per test result in just one e-mail). To specify an e-mail recipient, go to the main Global Settings menu in BenchVue and select "Settings".
Execute Batch File - Execute a custom batch file upon first limit failure (multiple failures per test result in executing the batch file just once). After enabling this mode, click ... and browse to the file location where you have stored custom batch files that you have created.