Programming instructions

Chapter 17 Shaking Hands with a Digital Partner

LabVIEW Data Acquisition Basics Manual 17-4

National Instruments Corporation

If you use more than one port or grouping ports for digital output on

DAQ devices other than DIO-32 Series devices, connect only the

handshaking signals of the last port in the port list, as shown in Figure 17-2.

Figure 17-2.

Connecting Digital Signal Lines for Digital Output

There are two types of digital handshaking: non-buffered and buffered.

Non-buffered handshaking is similar to nonlatched digital I/O because

LabVIEW updates the digital lines immediately after every digital or

handshaked pulse.

Note

For the DIO-32HS devices, LabVIEW returns immediately after storing data in

its FIFO.

With buffered handshaking, LabVIEW stores digital values in memory to

be transferred after every handshaked pulse. Both non-buffered and

buffered handshaking transfer only one digital value after each handshaked

pulse. For basic digital applications, use non-buffered handshaking. Use

buffered handshaking when your application requires multiple

handshaking pulses to be created. By using a buffer with multiple

handshaking pulses, the software spends less time reading or writing data,

leaving more time for other operations.

Note

On the DIO-32 Series devices with non-buffered handshaking, you can group 1,

2, or 4 ports together. For buffered handshaking on the DIO-32 Series devices,

you can group only 2 or 4 ports together.

Port

ACK*

External Device

(last port in portList)

Port

ACK*

OBF*