The delay scan consists of multiple scan steps (AliITSOnlineSPDscanMultiple class, see SPDscan Package documentation). Detector configuration changes throughout the scan, applied in such a way that the delay settings change for each chip.
The purpose is to find the delay settings, that correspond to the highest multiplicity (efficiency).
The processing performed in the "AliITSOnlineSPDscanAnalyzer::GetDelay" method. This just returns the clock cycle value, where the multiplicity is the highest. The clock cycle value is given by:
if (miscCtrl == 192) : clockCycle = 2*delayCtrl
if (miscCtrl == 128) : clockCycle = 2*delayCtrl + 1
This is however taken care of automatically by the software, so in the output file for the update of the DCS configuration, the DAC values (miscCtrl and delayCtrl) are put directly.