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NIDisk User Guide

6. Simultaneous Acquisition/Playback

About Simultaneous Acquisition/Playback

NIDisk can perform simultaneous acquisition and playback when supported by the I/O

device. Simultaneous I/O is supported by most high-performance NI cards, including "E-

series" devices (e.g., DAQCard-6062E) and "M-series" devices (e.g., PCI-6251).

Applications include synchronized stimulus-response experiments and playbacks adapted

dynamically based on vocalization responses acquired during playback.

The acquisition and playback processes must physically start at the same time, but the two

processes can be offset either by inserting silence at the beginning of the playback signal (to

delay playback), or discarding an intial segment of the acquired signal (to "delay"

acquisition). Acquisition and playback processes need not be the same length. The I/O

process will proceed until both acquisition and playback have completed.

To precisely synchronize acquisition and playback processes, use an external trigger (see

below). The status signal IO_ACTIVE (see below) will be driven by the acquisition process.

Only the acquisition progress screen is displayed.

Simultaneous acquisition and playback can be controlled from SIGNAL via the SIMIO

command.

Note that concurrent I/O processes usually divide the bandwidth of the I/O device, e.g., a 500

kHz I/O device will typically support simultaneous one-channel acquisition and playback at

250 kHz per process. The PCI-6251 does not seem to have this limitation, and is capable of

1.5 MHz performance simultaneously on acquisition and playback.

National Instruments I/O devices do not support simultaneous processes of the same type,

e.g., two acquisition processes on the same device.

Performing Simultaneous Acquisition/Playback

To perform simultaneous acquisition/playback, select I/O | Acquire & Play on the NIDisk

menu. NIDisk displays the Acquisition/Playback parameter screen, which allows the user to

configure the acquisition and playback. NIDisk then displays the Acquisition/Playback

summary screen, which summarizes acquisition/playback parameters and allows the user to

initiate the I/O process.

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