ADLINK DAQe-2214 - Manual (Page 50)

38 Operation Theory
When the trigger signal occurs before the first M scans of data are
converted, the amount of stored data could be fewer than the orig-
inally specified amount in NumChan_counter * M_counter, as
illustrated in Figure 4-4. This situation can be avoided by setting
M_enable. If M_enable is set to 1, the trigger signal will be ignored
until the first M scans of data are converted, and it assures you M
scans of data under pre-trigger mode, as illustrated in Figure 4-5.
However, if M_enable is set to 0, the trigger signal will be
accepted any time, as shown in Figure 4-4. Note that the total
amount of stored data will always be equal to the number in the
M_counter because data acquisition does not stop until a scan is
completed.
Figure 4-4: Pre-trigger with M_enable=0 (Trigger occurs before M scans)
Acquisition_in_progress
Scan_start
AD_conversion
Scan_in_progress
(SSHOUT)(pin8 on CN2)
(M_Counter = M = 3, NumChan_Counter=4, PSC_Counter=0)
Acquired & stored data
(2 scans)
Operation start
Trigger