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Serial Interfaces for RS232, RS485, and RS422

National Instruments offers high-quality, reliable serial interfaces for communications with laboratory instruments, industrial devices, and embedded circuits using RS232, RS485, and RS422. NI serial interfaces work on all major PC platforms with a variety of port and isolation options. 

Series
Plug-In Controllers 
Series Interface Ports Serial Standard  
PCI-8430/2 PCI 2 RS232 More detail
PCIe-8430/2 PCI Express 2 RS232 More detail
PCI-8431/4 PCI 4 RS485, RS422 More detail

External Controllers 
Series Interface Ports Serial Standard  
NI USB-232 USB 1, 2, 4 RS232 More detail
NI USB-485 USB 1, 2, 4 RS485, RS422 More detail
NI ENET-232/2 Ethernet 2 RS232 More detail
NI ENET-485/4 Ethernet 4 RS485, RS422 More detail