Menu Tools > 
Start Communication Logging ...
Log file format
The available log formats are plain text (.txt), HTML for web browsers (.htm), or RTF Rich Text Format for Microsoft Word or Wordpad (.rtf).
•Plain text file (.txt) is a good choice if you expect your log files to become very large.
TIP: The Windows built-in Notepad editor can be very slow in opening and editing larger files. We recommend the popular Open Source editor Notepad++ as available at http://notepad-plus.sourceforge.net - it is a much faster and more powerful alternative.
NOTE: there is no size limit for Docklight log files besides the limits on your Windows PC. We have successfully tested Docklight in long-term monitoring / high volume applications and created log files with several GB size without any stability issues.
•HTML files (.htm) are more comfortable to analyze, because they include all the visual formatting of the Docklight communication windows (colors, bold characters, italic characters). However, the disk size for such a file will be larger than for a plain text format, and large HTML files will slow down common web browsers.
TIP: If you have specific requirements on the output format, you can customize the HTML output.
•RTF Rich Text Format (.rtf) is a good choice for both small and large log files with formatted text - both Microsoft Word and Wordpad can navigate through larger files fast and without appearing unresponsive.
NOTE: Due to the specifics of the RTF document format, Docklight cannot efficiently append new data to an existing log file, but needs to create a temporary copy of the existing log first, which can cause additional delays. It is also not supported to append new logging data with different colors & font settings than at the start of the file.
Log file directory and base name
Choose the directory and base file name for the log file(s) here. The actual file path used for the individual log file representations are displayed in the text boxes within the "Log file representation" frame.
Overwrite / append mode
Choose "append new data" if you do not want Docklight to overwrite existing log file(s). Docklight will then insert a "start logging / stop logging" message when opening / closing the log files. This is so that when in 'append mode' it is still possible to see when an individual log file session started or ended.
Representation
A separate log file may be created for each data representation (ASCII, HEX, ...). Choose at least one representation. The log files will have a ".txt" or ".htm" file extension. Docklight additionally adds the representation type to the file name to distinguish the different log files. E.g. if the user specifies "Test1" as the base log file name, the plain text ASCII log file will be named "Test1_asc.txt", whereas the plain text HEX log file will be named "Test1_hex.txt".
Disable communication window while logging
If you are monitoring a high-speed communication link or if you are running Docklight on a slow computer, Docklight may not be able to process all the transmitted data or may even freeze (no response to any user input).
Using this option to disable the communication window output while logging the data to a file. Docklight will run much faster, since the continuous display formatting and update requires considerable CPU time.
NOTE: For more information on high-speed applications, see also the section How to Increase the Processing Speed...