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