The AC422AT is a non-isolated RS-422/485 adapter card that plugs directly into the IBM PC bus. The AC422AT is transientprotected, features bi-directional handshake lines for RTS and CTS, and can drive up to 100 devices on a multidrop network. The AC422AT can be jumpered for operation as COM1, COM2, COM3, or COM4 and offers full hardware and software compatibility with IBM PC, XT, and compatible computers. The AC422AT use the same UART used in the AT model computers. Interface: RS-422/485 (9-pin, D-shell female connector).