How to View Time Stamps With Saved LabVIEW SignalExpress Data

Updated Jan 28, 2019

Reported In


  • SignalExpress

Issue Details

Where is the time stamp for my saved LabVIEW SignalExpress Data?


In SignalExpress you are given the option to save to an ASCII/LVM file, or to a HWS file.  Placing a Save to ASCII/LVM step and selecting the File Settings tab will give you the option to choose a Generic ASCII (.txt) file or a LabVIEW Measurement File (.lvm).  The LVM (LabVIEW Measurement) file will include a header containing test information specified by you (author, test name etc.), as well as general test information (start date and time, channels etc.).  Each channel will have a time column associated with it containing the absolute time in seconds (this is seconds elapsed since 12:00 a.m., Friday, January 1, 1904 Universal Time).  

If you select Generic ASCII (.txt) you will not get the header that the LVM file creates, but you will be given an option to change the delimiter (tab, column, etc.), the number of time columns (one universal time column, or one for each channel),  and the time axis (relative time from start of test or universal time in seconds).  Selecting universal time will use the same seconds elapsed method as the LVM file.  Both the LVM and Generic ASCII files can be opened in spreadsheet program, such as Excel.

Figure 1: File Settings For Generic ASCII File

The HWS file type allows you to view time stamps as well but this file type is not as universal as the ASCII/LVM file.  You must use a program that is compatible with the HWS file type, such as SignalExpress, to view your data.  In SignalExpress you can click the Data View tab in order to see your plotted data.  You can change the time stamp format by right clicking in the graph area and selecting Time Stamp.  From there you will have the option to choose IgnoreAbsolute, or Relative.  Take a look at the KnowledgeBase article What is the HWS File Format?  for more information about this file type.  Figure 2 below shows the time stamp options.

Figure 2: Time Stamp Options



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