The Serial Interface Device offers a number of options for connecting to serial hardware. You can choose from Ethernet, USB, PCI, PCIe, or ExpressCard interfaces to add up to 16 serial ports to your system. You can choose from common serial protocols, such as RS232, RS422, and RS485. The Serial Interface Device also offers various isolation, hyperthreading, and multiprocessor compatibility options. Some models also support 4- and 2-wire transceiver modes for full- and half-duplex communication. NI serial interfaces also appear as standard COM ports for compatibility with programs that use serial communications.