Under Ordinary Operating Conditions
| Amber | Green | Explanation |
| Off | On | Operating correctly |
| Blinking | On | Possible problem |
Problem Indicators
| Amber | Green | Explanation |
| Blinking | Off | Card is not open (Wire fault or self-test failure) |
| Blinking | On | Card has detected "beaconing" or hard error |
| On | On | Card has failed |
Sequence Of LED Light at Computer Startup
| Amber | Green | Explanation |
| Blinking | Blinking | Waiting for initialization |
| Off | Off | Card is being initialized or computer is off |
| Off | Blinking | Self-test OK; card waiting to open |
| Off | On | Card is open and operating correctly |
Notes:
- Beaconing - card's signal to other devices on the network that a hard error has occurred. The card can remove itself from the network and conduct self-tests to determine if it is causing the problem.
- Hard error - a problem that requires removal of the source of the error or reconfiguration of the network before the network can resume reliable operation.
- The card is open when it has established connection with other devices on the network.
- A wire fault is an error caused by a break or a short circuit in the cable that connects the card to its access unit.
This article was published in the 12 May 1997 "Information Alley".