Programming instructions

National Instruments Corporation 17-1 LabVIEW Data Acquisition Basics Manual

Shaking Hands with

a Digital Partner

You have just learned that in LabVIEW using non-latched (immediate)

digital I/O, you can use digital lines to acquire and generate data. But what

if you want to pass a digital pattern after receiving a digital pulse? In this

case, you should use

latched digital I/O

, also called

handshaking

. For

example, you may want to acquire an image from a scanner. The scanner

sends a pulse to your DAQ device after the image has been scanned and it

is ready to transfer the data. Then, your DAQ device reads a digital pattern,

which can be 8, 16, or 32 bits in length. Your DAQ device then sends a

pulse to the scanner to let it know the digital pattern has been read. The

scanner sends out another pulse when it is ready to send another digital

pattern. After your DAQ device receives this digital pulse, it reads the data.

This process repeats until all the data is transferred. As you can see, the

ability to handshake gives you the ability to synchronize digital data

transfer between your DAQ device and instrument.

The following list shows the DAQ devices that support digital handshaking.

• AT-MIO-16D

• AT-MIO-16DE-10

• 1200 Series devices

• DIO-24 (DAQCard, NB, and PC, including PnP)

• DIO-32F (NB and AT)

• DIO-32HS (AT and PCI)

• DIO-96 (PCI, NB, PCI, and PC, including PnP)

• Lab Series devices (NB, LC, and PC)

Note

Combining channel names configured in the DAQ Channel Wizard and

handshaking are not supported in LabVIEW 5.0.