National Instruments NI USB-6221 用户手册

Figures 4 through 7 show the connector pinouts for the USB-6221 OEM, 
USB-6229 OEM, USB-6251 OEM, and USB-6259 OEM devices.

Refer to the M Series User Manual at 

ni.com/manuals

 for more 

information about USB-6221/6229/6251/6259 signals and how to 
connect them.