8-Port RS-232/422/485 serial communications board
DNx-SL-508
4-port, RS-232/422/485 serial communications board
DNx-SL-501
4-port, synchronous serial communications, HDLC, and SDLC protocol support
DNx-SL-504
4-port, RS-232/422/485 serial communications board 4mbs
DNx-SL-501-804