Measurement Computing Data Acquisition Systems rev.10.4 - Manual (Page 88)

daqAdcSetRate
Also See: daqAdcSetAcq, daqAdcSetTrig, daqAdcArm, daqAdcSetFreq, daqAdcGetFreq
Format
daqAdcSetRate(handle, mode, state, reqValue, actualValue)
Purpose
daqAdcSetRate configures the acquisition scan rate using the selected device’s built-in acquisition pacer
clock.
Parameter Summary
Parameter Type Description
handle DaqHandleT Handle to device for which to set the scan rate
mode DaqAdcRateMode Sets the acquisition mode in terms of period or frequency
state DaqAdcAcqState Indicates the acquisition state which scan rate applies to
(either pre-trigger or post-trigger)
reqValue FLOAT Variable which indicates the requested acquisition scan rate
actualValue PFLOAT Variable which indicates the actual acquisition scan rate
Parameter Values
handle: obtained from the daqOpen function.
mode: see table below
state: see table below
reqValue: valid values for freq range from 0.0 to 1,000,000.0
actualValue: a pointer to a floating point number, ranging from 0.0 to 1,000,000.0
Parameter Type Definitions
mode-(DaqAdcRateMode)
Definition Description
DarmPeriod Sets requested scan rate in terms of period (nanoseconds)
DarmFrequency Sets requested scan rate in terms of frequency (hertz, or channel scans per second)
DarmExtClockPacer Sets external pacer clock divisor (WaveBook 516 only)
state-(DaqAdcAcqState)
Definition Description
DaasPreTrig Scan rate configuration is applied to pre-trigger acquisition state
DaasPostTrig Scan rate configuration is applied to post-trigger acquisition state
Returns
DerrNoError No error
Function Usage
The daqAdcSetRate function should be used if internally pacing an acquisition with a device’s built-in
pacer clock. This function configures the internal pacer clock to the appropriate scanning frequency or period.
When the internal pacing clock fires, a new channel scan will be initiated, starting with the first channel in the
channel scan group (see the daqAdcSetScan function for channel configuration). The specific period or
frequency during which these scans will be taken is determined by the acquisition scan rate setting.
For correct results, the daqAdcSetRate function must be called after
daqAdcSetClockSource
, daqAdcSetScan (or daqAdcSetMux), and
daqAdcSetTrig .
4.2-32 Daq API Command Reference 988594 Programmer’s Manual