Chapter 3 Hardware OverviewDAQCard E Series User Manual3-12 National Instruments CorporationIn low-hysteresis analog triggering mode, the trigger is generatedwhen the signal value is less than lowValue, with the hysteresisspecified by highValue.The analog trigger circuit generates an internal digital trigger basedon the analog input signal and the user-defined trigger levels. Thisdigital trigger can be used by any of the timing sections of theDAQ-STC, including the analog input, analog output, andgeneral-purpose counter/timer sections. For example, the analoginput section can be configured to acquire n scans after the analoginput signal crosses a specific threshold. As another example, theanalog output section can be configured to update its outputswhenever the analog input signal crosses a specific threshold.Digital I/OThe DAQCard E Series cards contain eight lines of digital I/O forgeneral-purpose use. You can individually configure each line throughsoftware for either input or output. At system startup and reset, thedigital I/O ports are all high impedance.The hardware up/down control for general-purpose counters 0 and 1 areconnected onboard to DIO6 and DIO7, respectively. Thus, you can useDIO6 and DIO7 to control the general-purpose counters. The up/downcontrol signals are input only and do not affect the operation of the DIOlines.Figure 3-9. Low-Hysteresis Analog Triggering ModehighValueTriggerlowValue
