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Physical Channel Syntax

Last Modified: January 31, 2020

Use this syntax to refer to physical channels and groups of physical channels in NI-DAQmx.

Physical Channel Names

Physical channel names consist of a device identifier and a slash (/) followed by a channel identifier. For example, if the physical channel is Dev1/ai1, the device identifier is Dev1, and the channel identifier is ai1. MAX assigns device identifiers to devices in the order they are installed in the system, such as Dev0 and Dev1. You also can assign arbitrary device identifiers with MAX.

For analog I/O and counter I/O, channel identifiers combine the type of the channel, such as analog input (ai), analog output (ao), and counter (ctr), with a channel number such as the following:



For digital I/O, channel identifiers specify a port, which includes all lines within a port:


Or, the channel identifier can specify a line within a port:


All lines have a unique identifier. Therefore, you can use lines without specifying which port they belong to. For example, line31 is equivalent to port3/line7 on a device with four 8-bit ports.

Physical Channel Ranges

To specify a range of physical channels, use a colon between two channel numbers or two physical channel names:



For digital I/O, you can specify a range of ports with a colon between two port numbers:


You also can specify a range of lines:



You can specify channel ranges in reverse order:




Physical Channel Lists

Use commas to separate physical channel names and ranges in a list as follows:

Dev1/ai0, Dev1/ai3:6

Dev1/port0, Dev1/port1/line0:2

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