DAQ VXI-SC-1102 Manual de Instruções descarregar pdf (Página 102)

Chapter 15 VXI-DAQ Devices

DAQ Hardware Overview Guide 15-4 www.ni.com

You can interface the VXI-MIO Series modules to an SCXI signal

conditioning and multiplexing system to acquire over 3,000 analog signals

from thermocouples, RTDs, strain gauges, voltage sources, and current

sources. You can also acquire or generate digital signals for communication

and control.

The digital I/O signals are DIO<0..7> and DGND. DIO<0..7> are the

signals making up the DIO port, and DGND is the ground reference signal

for the DIO port. You can program all lines individually to be inputs or

outputs.

Digital input applications include receiving TTL signals and sensing

external device states such as the state of the switch. Digital output

applications include sending TTL signals and driving external devices such

as the LED.

VXI-DAQ Signal Conditioning

VXI-DAQ signal conditioning behaves like traditional (external) SCXI,

but with some important differences:

• The VXI-MIO controls the VXI-SC-1000 and the VXI-SC

submodules using the VXI local bus. Up to two signal conditioning

submodules plug into a single carrier module.

• A VXI-SC-1000 consists of all of the physically contiguous modules

(and associated carrier modules) that are inserted to the right of a given

VXI-MIO device, which is the cabled device.

• Conditioned data is multiplexed onto a special VXI AI channel

(

ND_VXI_SC), rather than the user-addressable AI channels for the

MIO device.

• You can still cable an external SCXI to a VXI-MIO device and, in fact,

you can use it simultaneously with VXI-DAQ signal conditioning.

• Each VXI-DAQ module, as well as the carrier module, has a unique

VXI-DAQ logical address.

• Modules are numbered as follows: for a VXIbus chassis in the upright

position, the modules are numbered sequentially, first from top to

bottom (slot 1 to the left), then from left to right.

Although it is important to understand these differences, the NI-DAQ

programming model is the same, with one exception: if you are using the

C API, you must use the special AI channel (

ND_VXI_SC) to read your

conditioned data. In LabVIEW, however, the onboard channel string is

ignored when communicating with a VXI-SC-1000. In either case, you

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DAQ VXI-SC-1102 Manual de Instruções Página 102