Functions > di_sample_rate

Syntax 

di_sample_rate determines how fast sampled data is reported (the Sample RateAll DATAQ Instruments hardware products continuously sample data using a burst sampling technique. With the burst sampling technique, the board or hardware device samples data at one rate (referred to as the maximum sampling rate or burst rate) while your computer reports (i.e., displays and stores) this data at another rate (called the sample rate or throughput rate). The burst rate determines how fast the board or hardware device samples the data and the sample rate determines how fast the sampled data is reported.).

Note: di_sample_rate cannot be called while scanning. You should not directly call di_burst_rate when using di_maximum_rate and di_sample_rate. You MUST call di_burst_rate when sampling different channels at different rates. For the DI-245 or DI-2008, di_list_length must be called before di_sample_rate. If more than one channel is enabled, the returned rate will not exceed one tenth of the value returned by di_maximum_rate.

Syntax 

Parameters

desired_rate

When desired_rate is entered, an attempt is made to report data at that rate. The data will actually be reported at the closest achievable rate to the desired sample rate you requested. The actual sample rate is the value returned by di_sample_rate.

Note: The desired sample rate cannot exceed the value returned by the previous call to di_maximum_rate.

oversample

oversample is a pointer to a 32-bit integer that receives an oversampling factor that is needed to achieve the returned sample rate. The user is responsible for putting this value minus 1 into the counter fields of the di_inlist structure entries for all channels and passing an array of those structures as an argument to di_inlist before calling di_start_scan. If di_maximum_rate is called after di_sample_rate, the user must call di_sample_rate again, update the input list counters, and call di_inlist before starting a scan.

burst_div

burst_div is a pointer to a variable in which the function returns the burst rate divisor argument that was passed in di_burst_rate. A null pointer may be passed if the user does not need to know the burst rate divisor (this is usually the case).

Return Value

This function returns the actual Sample RateAll DATAQ Instruments hardware products continuously sample data using a burst sampling technique. With the burst sampling technique, the board or hardware device samples data at one rate (referred to as the maximum sampling rate or burst rate) while your computer reports (i.e., displays and stores) this data at another rate (called the sample rate or throughput rate). The burst rate determines how fast the board or hardware device samples the data and the sample rate determines how fast the sampled data is reported..

Dependencies

di_maximum_rate

di_inlist

Remarks

If di_open has not been called successfully or if the device has been closed, the return value for di_sample_rate is 0 and none of the arguments for di_sample_rate are used.

DI-1100, DI-1110, DI-1120, DI-2108, DI-4108, DI-4208, DI-4718B, and DI-4730 arguments and return values for sample rate are per channel values. Both di_list_length and di_inlist must be called first. Call di_maximum_rate first, and di_inlist again after di_sample_rate to set the counter values.

Sample Code

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