This is the module register Acquisition Control 0x8100

Run Mode:
    Software Controlled;   Start and Stop of acquisition takes place on setting/resetting the Acquisition control bit.
    S-IN Controlled; If the acquisition is armed then the run starts when the S-IN signal is asserted and stops when the S-IN signal is inactive. If the acquisition is disarmed then acquisition then the S-IN signal is ignored.
    First Trigger; If the acquisition is armed then the run starts on the first trigger pulse (rising edge on TRG-IN); this pulse is not used as a trigger, actual triggers start from the second pulse. The stop of run is software controlled.
    GPIO Controlled; As for S-IN control but using GPIO.

Acquisition:
    When in Software Controlled mode this acts as a run start/stop. For all other run modes the actual start/stop is controlled by an external signal as described. 



NOTE: At present only Software Control is supported by the acquisition system.