user manual

Digital I/O

To use digital I/O, insert a digital C Series I/O 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 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. 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 C Series I/O module and the capabilities of the

module.

Table 3. 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