Automatic equipment identification
（重定向自Car Track）
![RFID antenna used by trackside AEI readers](/Images/godic/202501/03/AEIreader3400.jpg")
![ACI plate 1](/Images/godic/202501/03/ACI_plate_13400.jpg")
![AEI tag affixed to the side of a freight car.](/Images/godic/202501/03/AEItag3400.jpg")
![ACI plate with older KarTrak color barcode. AEI tag can also be seen on side of car to the right and lower of ACI plate.](/Images/godic/202501/03/ACI_plate3400.jpg")
Automatic equipment identification (AEI) is an electronic recognition system in use with the North American railroad industry. Consisting of passive tags mounted on each side of rolling stock and active trackside readers, AEI uses RF technology to identify railroad equipment while en route.