The ability to use the PFI lines as static digital inputs and outputs is a feature found on NI M Series and X Series devices. However, different terminology is used for the terminal depending on the function for which you use the PFI line.
On the I/O connector, each terminal is labeled either PFI x
, or Px.y
. When a terminal is used as a timing or synchronization signal, it is called PFI x
, where x
is an integer. By contrast, when a terminal is used as a digital input or output, the terminal is labeled Px.y
, where x
is an integer representing the port number and y
is an integer representing the line number. The device pinout will allow you to see what the corresponding digital terminal is for each PFI line. Consult the user manual or the NI-DAQmx Help
to find the device pinouts.
For example, on a NI-6251, to use PFI0
as a digital input or output, you should choose P1.0
as the physical channel.
NI-6251 Device Pinout
In software, the digital port and lines are called out by name. For example, if line 0 on port 1 was to be used on a device with alias NI_6251, we would use NI_6251/port1/line0 to refer to this physical terminal. This same terminal could be called PFI0 if it were used for another purpose other than DIO.
DAQmx Create Virtual Channel VI