rs 485/8

[myz]

can pci485/8 work on 172.8kb/s?what is meaning '485/422'?

[Al_S]

The datasheet for PCI-485/8 (http://www.ni.com/pdf/products/us/3ser704-706.pdf) says the maximum transfer rate is 460 kb/s.
RS-485 and RS-422 are electrically compatible, but RS-485 is bi-directional and half-duplex (you can't transmit and receive at the same time). Rs-422 is uni-directional (it uses separate transmit and receive lines) and is typically implimented as full-duplex: you can transmit and receive at the same time.

[Ray K]

RS-422 is found primarily Macs and improved performance by using differential lines. RS-485 was an improvement over 422. See this KnowledgeBase for more information.

RS-485 can be used in half and full duplex modes. NI RS-485 ports configured for four-wire mode will do full duplex I/O and ports configured for any of the two wire modes will do half duplex. See the section on tranceiver modes in the Serial User Manual for more information.