Chapter 3 Hardware OverviewVXI-MIO Series User Manual3-14 National Instruments CorporationIn low-hysteresis analog triggering mode, the trigger is generated whenthe signal value is less than lowValue, with the hysteresis specified byhighValue.Figure 3-8. Low-Hysteresis Analog Triggering ModeThe analog trigger circuit generates an internal digital trigger based onthe analog input signal and the user-defined trigger levels. This digitaltrigger can be used by any of the timing sections of the DAQ-STC,including the analog input, analog output, and general-purposecounter/timer sections. For example, the analog input section can beconfigured to acquire n scans after the analog input signal crosses aspecific threshold. As another example, the analog output section can beconfigured to update its outputs whenever the analog input signalcrosses a specific threshold.Digital I/OThe VXI-MIO Series modules 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.highValueTriggerlowValue
