Although this information is documented in the respective Installation Guides, here is a summary of what the LED behavior indicates on common Digi USB products:
On all model AnywhereUSBs, the System Status LED should blink slow Green in normal operation.
Note: Specifically regarding the legacy AnywhereUSB/5, If the System Status LED is solid Orange, it may need to be factory reset (see AnywhereUSB factory reset procedure
On all model AnywhereUSBs, the USB Port LEDs reflect if they are connected to a host computer (solid Green) or not (Off). This behavior is independent of whether or not a USB device is attached to that port. Regarding the legacy AnywhereUSB/5, AnywhereUSB/2, AnywhereUSB/5 G2, and AnywhereUSB TS44, all USB ports will either be connected (solid Green) or not connected (Off) because these models may only be connected to one host computer at a time. Regarding the AnywhereUSB/5 M and AnywhereUSB/14 models, individual USB ports may or may not be connected, because these models support Multi-Host Connections (MHC).
The System Status LED should blink slow Green in normal operation, whether or not it's connected to a host computer.
The USB Port LEDs should always be solid Green, regardless if USB devices are attached.
Edgeport and Rapidport/4:
The System Status LED should blink slow Green in normal operation, when the Edgeport is installed and idle. When data is passing through the Edgeport, i.e. it's actually being used, the System Status LED should blink rapid Amber.
If the System Status LED blinks slow Red, or is Off, this suggests the Edgeport driver is not installed.
Note: It's normal to see quick Red flashes on the System Status LED when connecting a USB cable to the Edgeport.
The Hub LED on the Rapidport/4 should be solid Green in normal operation.
Hubport USB 2.0 Compact:
The System power LED should be solid Green when the unit is powered on, regardless if it's connected to a computer.
The Port status LEDs reflect whether a USB device is attached to that port (solid Green) or not (Off).