ADLINK Technology cPCI-9116 Podręcznik Użytkownika Pobierz pdf (Strona 51)

Operation Theory • 41

When an external trigger signal occurs before the first M scans of data are

converted, the amount of stored data could be fewer than the originally

specified amount of DIV_counter * M_counter, as illustrated in fig 12. 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 user of obtaining M scans of data under pre-trigger mode, as

illustrated in fig 13. However, if M_enable is set to 0, the trigger signal will be

accepted in any time, as illustrated in fig 12. Note that the total amount of

stored data is still always a multiple of DIV_counter (number of samples per

scan) because the data acquisition won’t stop until a scan is completed.

Acquisition_in_progress

Scan_start

AD_conversion

Scan_in_progress

(SSH_OUT)(pin47)

(M_Counter = M =

3, DIV_Counter=4, SC_Counter=0)

Acquired & stored data

(2 scans)

Operation start

ExtTrg(pin46)

Figure 12: Pre-trigger with M_enable = 0 (trigger occurs before M scans)

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ADLINK Technology cPCI-9116 Podręcznik Użytkownika Strona 51