Measurement Computing Data Translation DT3034, User Manual

Page: 89 / 178

Chapter 6
88
Specifying One or More Channels
You can specify one or two analog output channels in the analog output channel list, either
starting with DAC 0 or with DAC 1.
Values are output simultaneously to the entries in the channel list.
Output Ranges and Gains
Each DAC on the DT3034 board can output bipolar analog output signals in the range of
±10 V.
Through software, specify the range for the entire analog output subsystem as

10 V to +10 V,
and the gain for each DAC as 1.
If you are using a single-value operation, specify a gain of 1; refer to page 90 for more
information on single-value operations.
If you are using an analog output channel list, the subsystem defaults to a gain of 1 for each
channel; therefore, you do not have to specify the gain.
D/A Output Clock Sources
DT3034 boards provide two clock sources for pacing the output of each channel in the analog
output channel list:
• An internal D/A output clock that uses the 24-bit D/A Counter on the board.
• An external D/A output clock that you can connect to the screw terminal panel.
The following subsections describe the internal and external D/A output clocks in more
detail.
Internal D/A Output Clock
The internal D/A output clock uses a 20 MHz time base. Conversions start on the falling edge
of the counter output; the output pulse is active low.
Through software, specify the clock source as internal and the clock frequency at which to
pace the analog output operation.
The minimum frequency supported is 1.2 Hz (1.2 Samples/s). The maximum frequency
supported is 500 kHz (500 kSamples/s) with 100 mV steps or 200 kHz (200 kSamples/s) with
full-scale steps.
External D/A Output Clock
The external D/A output clock is useful when you want to pace analog output operations at
rates not available with the internal D/A output clock, if you want to pace at uneven intervals,
or if you want to start pacing when an external event occurs.