User's Manual

Digital I/O

To use digital I/O, insert a digital I/O C Series module into any slot on

the NI cDAQ-9172 chassis. The I/O specifications, such as number of lines,

logic levels, update rate, and line direction, are determined by the type

of C Series I/O module used. For more information, refer to the

documentation included with your C Series I/O modules.

Correlated vs. Static DIO Modules

Digital I/O module capabilities are determined by the type of digital signals

that the module is capable of measuring or generating. Static digital I/O

modules are designed for signals that change slowly and are accessed by

software-timed reads and writes. Correlated digital I/O modules are

for signals that change rapidly and are updated by either software-timed or

hardware-timed reads and writes. Correlated digital I/O modules can

perform the following tasks:

• Used in any slot—Software-timed reads and writes

• Used in slots 1 though 4—Digital waveform generation and

acquisition (correlated input/output)

• Used in slots 5 and 6—Counter/timer

• Used in slots 5 and 6—Access PFI signals

To determine the capability of digital I/O modules supported by the

NI cDAQ-9172 chassis, refer to the KnowledgeBase document,

C Series Modules Supported in the NI cDAQ-9172 CompactDAQ.

To access this KnowledgeBase document, go to

ni.com/info and enter

the info code

rdcdaq.

Available features, such as trigger and counter/timer, are determined by the

slot containing the digital I/O C Series module and the capabilities of the

module.

Table 4. Digital Module Slot Features

Slots Static DIO PFI

Counter/Timer

Digital

Waveform/Change

Detection

1 Yes — — Yes

2 Yes — — Yes

3 Yes — — Yes

4 Yes — — Yes