Chapter 3 Hardware Overview
DAQCard E Series User Manual
3-12
National Instruments Corporation
In low-hysteresis analog triggering mode, the trigger is generated
when the signal value is less than
lowValue
, with the hysteresis
specified by
highValue.
The analog trigger circuit generates an internal digital trigger based
on the analog input signal and the user-defined trigger levels. This
digital trigger can be used by any of the timing sections of the
DAQ-STC, including the analog input, analog output, and
general-purpose counter/timer sections. For example, the analog
input section can be configured to acquire n scans after the analog
input signal crosses a specific threshold. As another example, the
analog output section can be configured to update its outputs
whenever the analog input signal crosses a specific threshold.
Digital I/O
The DAQCard E Series cards contain eight lines of digital I/O for
general-purpose use. You can individually configure each line through
software for either input or output. At system startup and reset, the
digital I/O ports are all high impedance.
The hardware up/down control for general-purpose counters 0 and 1 are
connected onboard to DIO6 and DIO7, respectively. Thus, you can use
DIO6 and DIO7 to control the general-purpose counters. The up/down
control signals are input only and do not affect the operation of the DIO
lines.
Figure 3-9. Low-Hysteresis Analog Triggering Mode
highValue
Trigger
lowValue
