There are times when it is best to open a Client in a read-only mode to eliminate the possibility that a Client will affect a device or database. The Client event start up script to set the Client mode to read-only is an easy way to accomplish this. Similar to the buttons in the Designer, this function can be used to set Disconnected, Read Only, and Read/Write modes in any script in Ignition that runs in a Client.
To set the Client to be Read-Only
From the Designer, go to Project Browser > Scripts > Client Event Scripts. The Client Event Scripts window is displayed.
In the Startup script enter this code: system.util.setConnectionMode(2) where 2 means read-only.
Click OK. The start-up script will run the next time a user opens the Client, resulting in the Client being read-only.