We're experiencing challenges connecting to OPC Servers with Mango and would need to know where to get more documentation. Not all OPC Servers require authentication.
Good question! Alas, I'm not too sure. i can tell you that the OPC module is using the org.openscada OPC version 0.9 library to actually do the OPC protocol. I have very limited experience with OPC devices. It looks like you could modify a Mango/bin/ext-available script to set the log level for the logger in the library to a lower level by change its JAVA_OPTS to
-Dorg.slf4j.simpleLogger.defaultLogLevel=debugor put a config file someplace: https://stackoverflow.com/questions/14544991/how-to-configure-slf4j-simple
I'm not sure I found the ideal place to explore v0.9 of the source code for the library on the web.