LED indicators

Red LEDRed LED
Steadily on or off
Startup phase (approx. 5 seconds). During this time, the firmware can be upgraded using the Netloader program.
Blinking, at 4 pulses per second
The XnTcp is idle, waiting for a client.
Blinking, at 1 pulse per second
The XnTcp is serving a client.

Green LEDGreen LED (on the RJ-45 socket)
Off
Ethernet link not established. Either the RJ-45 cable is unplugged or defective; either all the other nodes on the LAN (e.g. the PC) are switched off.
On
Ethernet link properly established.

Yellow LEDYellow LED (on the RJ-45 socket)
Off
No traffic detected on the Ethernet.
On (pulsing)
The LED glows each time an Ethernet packet (originating from/directed to any node on the Ethernet) is detected.