Measurement Computing WaveBook rev.3.0 - Manual (Page 209)

WaveBook User’s Manual, 6-24-99 daqX API - Command Reference D-13
daqAdcSetTrig
DLL Function daqAdcSetTrig(DaqHandleT handle, DaqAdcTriggerSource triggerSource, BOOL rising,
WORD level, WORD hysteresis, DWORD channel);
C daqAdcSetTrig(DaqHandleT handle, DaqAdcTriggerSource triggerSource, BOOL rising,
WORD level, WORD hysteresis, DWORD channel);
Visual BASIC VBdaqAdcSetTrig&(ByVal handle&, ByVal triggerSource&, ByVal rising&, ByVal level%,
ByVal hysteresis%, ByVal channel&)
Delphi daqAdcSetTrig(handle:DaqHandleT; triggerSource:DaqAdcTriggerSource; rising:longbool;
level:WORD; hysteresis:WORD; channel:DWORD)
handle Handle to the device for which the ADC acquisition trigger is to be configured.
triggerSource Sets the trigger source.
rising Boolean flag to indicate the rising or falling edge for the trigger source
level The trigger level (in A/D counts) for an analog level trigger
hysteresis hysteresis value for analog level trigger (if selected)
Parameters
channel Channel for which the analog level trigger(if selected) is to be detected.
Returns DerrNoError No error (see the API Error Codes table at the end of this chapter).
See Also daqAdcSetAcq
Program References ADCEX1.C, DACEX1.C, DAQEX.FRM (VB), ADCEX.PAS, ERREX.PAS (Delphi)
Used With All devices
Description
daqAdcSetTrig sets and arms the trigger of the A/D converter. Several trigger sources and several mode flags can be used for a variety
of acquisitions. daqAdcSetTrig will stop current acquisitions, empty acquired data, and arm the Daq* using the specified trigger.
Trigger detection for the given trigger source will not begin until the acquisition has been armed with the daqAdcArm function. Trigger
sources may be defined as follows:
DatsImmediate - Trigger the acquisition immediately upon issuance of the daqAdcArm function. This trigger mode is used to begin
collecting data immediately upon configuration of the acquisition.
DatsSoftware - Trigger the acquisition upon issuance of the daqAdcSoftTrig function. This trigger mode can be used to initiate a trigger
upon some form of user or application program input.
DatsAdcClock
- Trigger the acquisition upon ADC pacer clock input. This trigger mode can be used to synchronize the trigger event
with the ADC pacer clock.
DatsExternalTTL
- Trigger the acquisition upon sensing a rising or falling (depending on state of rising flag) signal on an external
TTL input signal (trig0 - pin 25 on P1).
DatsHardwareAnalog
- Trigger upon detection of a rising or falling (depending on the state of the rising flag) analog signal (whose
count is defined by the level parameter). This trigger mode is detected in hardware to allow generally faster acquisition frequencies than
the DatsSoftwareAnalog trigger source. However, use of this mode is restricted to channel level triggering on only the first channel
within the channel scan (defined by the channel parameter).
Note: This DatsHardwareAnalog mode is not available on Daq PCMCIA product lines.
DatsSoftwareAnalog
- Trigger upon detection of a rising or falling (depending on the state of the rising flag) analog signal (whose
count is defined by the level parameter). This trigger mode is detected in software and generally will not allow the acquisition speeds of
the DatsHardwareAnalog trigger source. However, this mode has no trigger channel restrictions. Any valid channel in the scan group
can be configured as the trigger channel by specifying it in the channel parameter.
Note: The level parameter is only used for the analog trigger modes. level is a count representing the A/D count level trigger
threshold to be passed through in order to satisfy the analog trigger event. A number of factors are used to determine its proper
value. For help in calculating this analog count level properly, see the daqAdcCalcTrig function.