National Instruments NI cDAQTM-9138, User Manual

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© National Instruments | 1-37
NI cDAQ-9138/9139 User Manual
Using the cDAQ Chassis
The cDAQ chassis consists of four parts—C Series I/O module(s), the cDAQ module interface,
the STC3, and the processor board—as shown in Figure 1-21. These components digitize
signals, perform D/A conversions to generate analog output signals, measure and control digital
I/O signals, and provide signal conditioning.
Figure 1-21. Block Diagram
C Series I/O Module
National Instruments C Series I/O modules provide built-in signal conditioning and screw
terminal, spring terminal, BNC, D-SUB, or RJ-50 connectors. A wide variety of I/O types are
available, allowing you to customize the cDAQ chassis to meet your application needs.
C Series I/O modules are hot-swappable and automatically detected by the cDAQ chassis.
I/O channels are accessible using the NI-DAQmx driver software.
Because the modules contain built-in signal conditioning for extended voltage ranges or
industrial signal types, you can usually make your wiring connections directly from the C Series
I/O modules to your sensors/actuators. C Series I/O modules can sometimes provide isolation
from channel-to-earth ground and channel-to-channel.
For more information about which C Series I/O modules are compatible with the cDAQ chassis,
refer to the
C Series Support in NI-DAQmx document by going to
ni.com/info
and entering
the Info Code
rdcdaq
.
Parallel versus Serial DIO Modules
Digital I/O module capabilities are determined by the type of digital signals that the module is
capable of measuring or generating.
•
Serial digital I/O modules are designed for signals that change slowly and are accessed by
either software-timed or hardware-timed reads and writes.
• Parallel digital I/O modules are for signals that change rapidly and are updated by either
software-timed or hardware-timed reads and writes.
For more information about digital I/O modules, refer to Chapter 4, Digital Input/Output
and PFI .
C S erie s
I/O Mod u le
C S erie s
I/O Mod u le
cDAQ Mod u le
Interf a ce
S TC 3
Proce ss or
R S -2 3 2
R S -4 8 5/422
MXI Expre ss
U S B
VGA
Ethernet