In order to be able to double-click a relay in DavLink using a mouse, you have to enable this feature.
To do so, launch DavLink and click on the Key icon in its top menu (DavLink Logon/Logoff).
Then, at the logon screen, enter SUPER for username and SSSSSSSS for password. You will now be logged on.
Next, go in the top menu and click on Setup, then Options. You will see the following popup screen:
Now, select the first item in the property box and go click on the browse button at the bottom.
There are 3 relay control possibilities which are as follow: 0 is no mouse click control, 1 is one-click operation, and 2 is double-click operation.
Please note that activating relay mouse-click control may be somewhat dangerous since someone could accidentally turn on or off a relay, which could therefore cause important equipment shutdown or start-up. Double-click control is safer than Single-click control. If you select Single-click control, a warning sign will appear to remind you to be careful.