Brown
From PLC Wiki
Brown (System Operational):
The brown color indicates the fact that hardware is satisfactorily running and accumulating data actively. No immediate action is required, but it is advisable to monitor the hardware performance regularly so as to ensure that its optimal operation should be possible and improve identification of the potential problems at an early stage. This will thereby maintain system reliability and prevent any forms of unplanned downtime.
* This means that hardware is operating properly and data is being collected.
* No action is required at once, but routine performance monitoring is encouraged.