DAQ VXI-SC-1102 Bedienerhandbuch PDF herunterladen (Seite 43)

Chapter 4 516 Devices and DAQCard-500/700 Devices

National Instruments Corporation 4-3 DAQ Hardware Overview Guide

are not available on the I/O connector for the 516 devices and

DAQCard-500.

• Counter 1 is available for general-purpose counting functions.

• Counter 2 is available for general-purpose counting functions.

Data acquisition timing involves the following timing signals:

•A conversion pulse is a signal that generates a pulse once every sample

interval, causing the device to initiate an A/D conversion. This signal

can be generated by the onboard, programmable sample-interval clock

supplied by the MSM82C54 Counter/Timer, or can be supplied

externally through the I/O connector EXTCONV* input. You can

select external conversion pulses by calling

DAQ_Config. If you do

not want to use external conversion pulses, you should disconnect the

EXTCONV* pin on the I/O connector to prevent extra conversions.

•A timebase clock is a clock signal that is the timebase for the

MSM82C54 sample-interval counter. Counter 0 of the MSM82C54

uses a 1 MHz clock as its timebase.

See your device user manual for more information regarding these signals.

516 Devices and DAQCard-500/700 Digital I/O

The 516 devices and DAQCard-500 have one 4-bit digital input port and

one 4-bit digital output port. The DAQCard-700 contains one 8-bit digital

input port and one 8-bit digital output port. The digital I/O ports are labeled

DIN and DOUT on the I/O connector, as shown in the appropriate device

user manual. The ports are referred to as ports 0 and 1 by the Digital I/O

functions, in which:

• DOUT = port 0

• DIN = port 1

You can program ports 0 and 1 for no-handshaking mode only. You can use

port 0 for no-handshaking digital output mode. You can use port 1 for

no-handshaking digital input mode.

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DAQ VXI-SC-1102 Bedienerhandbuch Seite 43