4-Port, PCI, Isolated, RS485/RS422 Serial Interface Device—The PCI‑8433/4 is a high-performance industrial interface for high-speed, port‑to‑port isolated communication with RS485 and RS422 devices. It features high-performance DMA transfers, multithreading, and multiprocessor support. You can also select between 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.