The release latch on the SAN Volume Controller models 2145-8G4, 2145-8F4, and 2145-8F2 gives you access to the light path diagnostics panel, which provides a method for determining the location of a problem.
After pressing the release latch on the operator-information panel, you can slide the light path diagnostics panel out to view the lit LEDs. The LEDs indicate the type of error that has occurred. See MAP 5800: Light path for more detail.
To retract the panel, push it back into the node and snap it into place.