Chapter 2
NI 5450 Overview
©
National Instruments Corporation
2-19
NI PXIe-5450 User Manual
Multichannel Configuration
The NI 5450 has two channels that can be configured as active by calling
the niFgen Configure Channels VI or the
niFgen_ConfigureChannels
function with a string containing the channel(s) that you wish to activate.
You must configure the channels immediately after calling the niFgen
Initialize VI or the
niFgen_init
function. The niFgen Configure
Channels VI or the
niFgen_ConfigureChannels
function cannot be
called after the session has been committed. If a channel is inactive, it will
maintain its output voltage and state until it is made active again or until the
device is reset.
The NI 5450 has two memory banks, one for each channel. When the
niFgen Configure Channels VI or the
niFgen_ConfigureChannels
function is called to configure only one channel as active, both channel
memory banks will be configured. This allows you to use the entire
onboard memory for one channel of generation.
Configuring Channels for OSP
The NI 5450 supports one channel of real or complex baseband OSP
generation. When the OSP is enabled, only one channel may be configured
as active. Individual OSP properties can be configured using the I and
Q channel strings (“I” and “Q”, respectively).
Multichannel Waveform Allocation
A
waveform
consists of all of the data to be generated on all active channels
of a device. A waveform is allocated on a per–device basis, and when
waveform allocation occurs, space is allocated on the device onboard
memory for each channel. Waveform data must therefore be the same size
for each channel.
Because waveforms contain data for all channels, you can only generate
one script, sequence, or arbitrary waveform at a time for all active channels
of the device; you
cannot
generate separate scripts, sequences, or arbitrary
waveforms on different channels at the same time.
Writing Data
On the NI 5450, data can either be written to channel 0 and
1 independently, to I and Q independently, or to both
channels simultaneously.
