Pinout Terminology and Definitions for NI DAQ Devices


This article explains how to read and understand the pinout diagram and terminology for an NI DAQ cable, accessory, device or module.


The pinout diagram for your DAQ product describes which pins should be used for what functionality. Below is a listing of the standard terminology used and a brief description of how it can be used. This is not intended exhaustive collaboration of all terms. This document should provide a brief introduction to the terminology. For more information, see the related links below or consult your product manual.

Note: "#" refers to an integer value typically starting at 0.


Pinout Terminology and Definitions
Pin Type Description

AI #(+-)

Analog Input: This is usually followed by a number corresponding to a channel number. For instance, if your DAQ card has 16 analog input channels, your pinout diagram probably shows positive and negative terminals for AI 0 through AI 15 located throughout the connector.

AO #(+-)

Analog Output: Same description as analog input, but for analog output instead of analog input. Never try to send a signal in on an analog output line as this might damage the card.

P#.# (ex: P0.0)

DIO refers to digital input and output. These lines are used for both input and output of digital signals. When it says P#.#, the first number refers to the port and the second refers to the line. For instance, P1.2 means Port 1 Line 2. Each port has eight lines. So, if your DAQ card has 24 digital I/O lines, it would contain P0.0 through P3.7.


These refer to the corresponding operation's ground terminal.


The AI SENSE is a common reference point for certain input terminal configurations. For instance, the negative terminal might connect to this pin in a Nonreferenced Single-Ended input terminal configuration.


This pin is used for an external clock for analog output.

+5 V

This pin provides a constant 5 Volt signal typically used for excitation.


PFI lines are programmable function interfaces. For a detailed description about what you can do with PFI lines, consult this KnowledgeBase article. These pins usually have a counter associated with them as well.

Ctr # Source

The source counter is normally used for a digital trigger or a timing source. The number refers to the counter number. Typically, counters have a counter source, counter gate, and counter out.

Ctr # Gate

The gate counter is used to control the counter input. The counter gate is often used for frequency and period measurement.

Ctr # Out

The out counter is used for counter output. If you want to generate a digital pulse train, a Ctr # out would probably be the best option for you.


This line is used for an external strobe. For instance, a microprocessor might output a strobe signal that you might want to use as an external clock.


No Connect. Do not connect signals to these terminals.


These pins are used for common references. Note that this can also be tied to ground.