The Attachment Unit Interface [AUI] is a 15 pin D connector used with Ethernet. The pinout for the 15 pin D is shown below.
The AUI is used to transition between a network card and Ethernet back bone [cable].
The interface between the Ethernet/IEEE 802.3 controller and the baseband transceiver or
broadband modem.
Apple Computer AUI Pinout; for the AUI connector as found on an Apple Computer
A 15-pin 'D' connector is really called a D-Sub 15 or DA15, and not a DB15.
| Pin Number | Pin name | Signal Function |
| 1 | GND | Control In Circuit Shield |
| 2 | CI+ | Control In Circuit A |
| 3 | TX+ | Data Out Circuit A |
| 4 | GND | Data In Circuit Shield |
| 5 | RX+ | Data In Circuit A |
| 6 | GND | Voltage Common |
| 7 | NC | Not Used |
| 8 | GND | Ground, or Not Used |
| 9 | CI- | Control In Circuit B |
| 10 | TX- | Data Out Circuit B |
| 11 | GND | Data Out Circuit Shield |
| 12 | RX- | Data In Circuit B |
| 13 | +12v | Voltage Plus |
| 14 | GND | Voltage Shield |
| 15 | NC | Not Used |
Although this page indicates a 15-pin Dsub connector, Dsub connectors are being used less and less in products.
There are many other connectors that are physically smaller and have better frequency characteristics than the typical Dsub.
D-Sub-miniature Connector page for D-Sub Connector Manufacturers.
Back to the 10/100 Base Ethernet page, or 1000 base Ethernet page for additional
pinout tables and interface descriptions.
Note that some manufacturers will omit unused pins from the pinout list.
Connector terminals not referenced in the pinout list are not used.
For reference, see a Cisco Ethernet AUI port pinout table below showing different signal names.
So if a NIC card shows 14 signals in the pinout table while a LAN card shows 15; as long as pin 15 is unused and they both reside on a 15-pin Dsub your safe.
The AUI interface will always indicate 15 pins, because the cable uses a 15 pin connector.
This is another variation of the pin out for an AUI interface.
This particular table of signal assignments is from Cisco.
Although the pin outs are the same as shown above, but ordered differently.
The pin names are also different, but the descriptions match between the tables.
| Pin | Ethernet I/O | Signal |
|---|---|---|
| 3 | DO-A | Data Out Circuit A |
| 10 | DO-B | Data Out Circuit B |
| 11 | DO-S | Data Out Circuit Shield |
| 5 | DI-A | Data In Circuit A |
| 12 | DI-B | Data In Circuit B |
| 4 | DI-S | Data In Circuit Shield |
| 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 |
| 13 | VP | Voltage Plus |
| 14 | VS | Voltage Shield (L25 and M25) |
| Shell | PG | Protective Ground |
Pin 15 is not used and not shown in the pin out table. The shell is the connector shell or cover.
Although this page indicates a 15-pin Dsub connector, Dsub connectors are not being used much in newer products.
There are many other connectors that are physically smaller and have better frequency characteristics than the typical Dsub.
Return to the 10/100 Base Ethernet page, or 1000 base Ethernet page for additional
pinout tables and interface descriptions.
Note that some manufacturers will omit unused pins and signal assignments from the pin-out list.
Information related to Dsub connectors;
Dsub Connector Physical Sizes
Dsub Connector Pin Spacing and locations.
D-Sub-miniature Connector Manufacturers
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