It can be done easily from the Parallels RAS Console.
Right-click on Agent > Troubleshooting > Logging > Configure
LogLevel – Shows which log level is turned on right on the selected component.
Retrieve – Allows you to take a particular log (gateway or pa or tsagent) and save it as .zip file into required folder.
Clear – Delete log for the particular component.
To configure logging:
Standard is enabled by default.
Extended (lvl4) and Verbose (lvl5) can be switched on for several time sets as on the screenshot above.
Logging Level can also be changed in Settings > Global Logging