User manual

Programmer’s Guide Page 31 of 66
delayTime of the function AcqrsD1_configHorizontal is replaced by “StartDelay” and “StopDelay”
nbrSamples and nbrSegments of the function AcqrsD1_configMemory are replaced by “NbrSamples” and
“NbrSegments” in the function AcqrsD1_configAvgConfig.
The values nbrSamples, startDelay and stopDelay must be integer multiples of the „acquisition block size‟,
which is always 16 in the AP101, and 32 in the AP201. If the supplied value is not an integer multiple of the
„acquisition block size‟, it is truncated to the next lower integer multiple. Thus, nbrSamples = 250 will be
truncated to 240 (15 * 16) on an AP101, and to 224 (7 * 32) on an AP201. You can query the actual value
with the function AcqrsD1_getAvgConfig.
The value startDelay controls the time between the trigger and when the first digitized data sample is stored.
The stopDelay permits the addition of an extra delay to the dead time between the acquisition of subsequent
waveforms. Its minimum value may be zero.
Although not shown here, a call to AcqrsD1_configControlIO can be made in order to set a trigger veto
time to be respected after the receipt of a Prepare for Trigger signal on a Control I/O connector.
Also not shown, is a call to the function AcqrsD1_configAvgConfig to set a timeout value for the
automatic completion of a segment in case the real trigger never arrives.
3.9. Configuring TC8xx Time-to-Digital Converters
Use the following short code fragment for a device configuration:
// Configure
long i, n_chan, slope = 0;
double trigLevel = 0.2;
double timout = 0.1;
Acqrs_getNbrChannels(instrumentID, &n_chan);
for( i=0; i< n_chan; i++)
AcqrsT3_configChannel(instrumentID, i+1, slope, trigLevel, 0);
AcqrsT3_configChannel(instrumentID, -1, trigSlope, trigLevel, 0);
Comments:
Channel numbers run from 1 to nbrChannels, not from 0! The common channel uses the number –1.
The configuration functions are protected against illegal or incoherent values. Thus, the system might adapt the
values you ask for. The 'query' counterpart of this function, AcqrsT3_getChannel, can be interrogated to learn
what the driver did to the values.
The granularity of a threshold value setting is limited by the hardware that uses a 12-bit DAC covering the
desired range.
3.10. Data Acquisition
Instrument operation is preceded by configuring the instrument parameters and then starting the acquisition
sequence. New settings are only loaded into the module when the acquisition is started; there is one exception to this
rule as discussed for analyzer user gate definition in section 3.5.2 Readout configuration.
Similarly, you initiate an averaging operation by configuring the instrument parameters, including those that control
the averaging, and then starting the combined acquisition/averaging sequence. The Averager module resets the
accumulation buffers and then acquires the requested number of waveforms, each preceded by a front-panel trigger
signal, without any software intervention. The AcqrsD1_acquireEx function allows an AP100/AP200 Averager to
acquire additional data without resetting the accumulation.
Until the operation is terminated, your application is free to execute other tasks. There are several methods of
detecting when the acquisition/averaging operation has ended. Finally, you read the averaged waveform with the
function AcqrsD1_readData as described below.
If you want to acquire several (averaged) waveforms under the same conditions, there is no need to call the
AcqrsXX_config… functions again. It is sufficient to execute a loop over the “start, wait, read” functions. In
principle a subsequent start will happen considerably faster than the first one that was required to load the full
configuration.