Definition of AUI connector in The Network Encyclopedia.
What is AUI Connector?
AUI is an acronym for Attachment Unit Interface connector, a standard 15-pin connector device for thicknet or 10Base5 cabling. The AUI connector on the free end of the drop cable attaches to the DB15 connector on the network interface card (NIC). The NIC has an AUI port connector for connecting the drop cable.

The other end of the drop cable typically connects to a transceiver. The transceiver is then joined to the thicknet cabling using a vampire tap that pierces the cable jacket and insulation to make a connection.
Attachment Unit Interface (AUI) pinout
An AUI connector is a DA-15 (D-subminiature). It has a sliding clip in place of the thumbscrews normally found on a D-connector to hold two connectors together. This clip permits the MAU and MAC to be directly attached to one another even when their size and shape would preclude the use of thumbscrews.
Pin | Signal | Description |
---|---|---|
3 | DO-A | Data Out Circuit A |
10 | DO-B | Data Out Circuit B |
11 | DO-S | Data Out Circuit Shield (not used) |
5 | DI-A | Data In Circuit A |
12 | DI-B | Data In Circuit B |
4 | DI-S | Data In Circuit Shield |
7 | CO-A | Control Out Circuit A (not used) |
15 | CO-B | Control Out Circuit B (not used) |
8 | CO-S | Control Out Circuit Shield (not used) |
2 | CI-A | Control In Circuit A |
9 | CI-B | Control In Circuit B |
1 | CI-S | Control In Circuit Shield |
6 | VC | Voltage Common (0 V) |
13 | VP | Voltage Plus (+12 V) |
14 | VS | Voltage Shield (not used) |
Shell | PG | Protective Ground |