DAQ VXI-SC-1102 Manual de Instruções descarregar pdf (Página 77)

Chapter 14 SCXI Hardware

National Instruments Corporation 14-3 DAQ Hardware Overview Guide

If you use the SCXI-1200 DAQ module in multiplexed mode, it also has

access to the multiplexed output of all analog input modules in the chassis

that are operated in multiplexed mode.

If you use an MIO or AI device, Lab or 1200 device (except for the

DAQPad-1200), or an SCXI-1200 DAQ module, you can multiplex all the

analog input channels in the SCXI chassis to one onboard channel

dynamically during a timed acquisition. The SCXI functions program the

chassis with a module scan list that dynamically controls which module

sends its output to the SCXIbus during a scan. You can specify that the

modules be scanned in any order and specify an arbitrary number of

channels for each module; however, the channels on each module must be

scanned in consecutive, ascending order.

By default, when you cable a DAQ device to a multiplexed module, the

multiplexed output of the module (and all other multiplexed modules in the

chassis) appears at analog input channel 0 of the DAQ device.

You can use more than one SCXI chassis connected by a cable with one

MIO or AI device (except parallel ports) if the modules operate in

multiplexed mode. You must use one SCXI-1346 multichassis adapter for

each additional chassis (refer to your SCXI module user manuals). You also

should set a unique address for each chassis. The multichassis adapter

scheme sends the output of the module in the first chassis to analog input

channel 0 of the MIO or AI device, the output of the module in the second

chassis to analog input channel 1 of the MIO or AI device, and so on. When

you want to acquire data from the additional chassis, you must specify the

correct onboard MIO or AI device channel in the channel scan list that you

pass to the SCAN functions.

You can operate the SCXI-1100, SCXI-1101, SCXI-1102, and SCXI-1122

modules only in multiplexed mode.

Multiplexed Mode for the SCXI-1200

In multiplexed mode, the SCXI-1200 can access the analog bus on the

SCXI backplane. When you configure other analog input modules in the

chassis for multiplexed mode, the SCXI functions can multiplex their input

channels and send them on the analog bus on the SCXI backplane. So, if

you configure the SCXI-1200 for multiplexed mode, you can use it to read

the multiplexed output from other SCXI analog input modules in the

chassis. In addition, you can multiplex the analog input channels on the

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DAQ VXI-SC-1102 Manual de Instruções Página 77