Measurement Computing Data Translation DT3010 Series, User Manual, Page: 126 / 232

Principles of Operation
125
Analog Threshold Trigger
For analog output operations, an analog trigger event occurs when the DT3010 Series board
detects a transition from above a threshold level to below a threshold level (falling edge), or a
transition from below a threshold level to above a threshold level (rising edge). The following
analog threshold trigger sources are available:
• External Analog Trigger input signal – This trigger source is supported by the DataAcq
SDK; it is not supported by the DT-Open Layers Class Library.
Connect an external analog signal to screw terminal 107 on the DT740 screw terminal
panel, screw terminal 39 on the STP268 screw terminal panel (attached to connector J1), or
screw terminal 15 on the STP268-EC screw terminal panel. Using software, specify the
trigger source as either a rising-edge (OL_TR1 for DataAcq SDK users) or
falling-edge analog threshold trigger (OL_TR2 for DataAcq SDK users).
• One of the analog input channels after gain is applied . Using software, specify the trigger
source as either a positive threshold trigger or a negative threshold trigger.
Using software, specify the analog input channel used as the analog threshold trigger as
the first channel in the analog input channel list; refer to
page 106 for more information.
On DT3010 Series boards, the threshold level is set using a dedicated 8-bit DAC (the
second D/A subsystem); the hysteresis is fixed at 50 mV. Using software, program the
threshold level by writing a voltage value to the DAC of the second analog output
subsystem; this value can range from
−
10 V to +10 V.
Note: If you are using an analog threshold trigger to trigger both the A/D and the D/A
subsystems, ensure that you use the same analog trigger type for both subsystems (either
external or one of the analog input channels). The polarity of the triggers, however, can be
different.
Analog Output Conversion Modes
DT3010 Series boards support the following conversion modes:
• Single-value operations are the simplest to use but offer the least flexibility and efficiency.
Use software to specify the range, gain, and analog output channel (among other
parameters), and output the data from that channel. For a single-value operation, you
cannot specify a clock source, trigger source, or buffer.
Single-value operations stop automatically when finished; you cannot stop a single-value
operation.
• Continuous analog output operations take full advantage of the capabilities of the
DT3010 Series boards. In this mode, you can specify an analog input channel list, clock
source, trigger source, buffer, and buffer wrap mode. Two continuous analog output
operations are supported: continuously-paced and waveform generation mode. These
modes are described in the following subsections.