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42 • Operation Theory

Acquisition_in_progress

Scan_start

AD_conversion

Scan_in_progress

(SSH_OUT)(pin47)

(M_counter = M = 3, DIV_counter=4, SC_counter=0)

Aquired data

Acquired & stored data

(M scans)

Trigger signals which occur in the shadow

region(the first M scans) will be ignored

Operation start

ExtTrg(pin46)

The first M scans

Figure 13: Pre-trigger with M_enable = 1

Note: The SC_counter must be set to 0 in pre-trigger acquisition mode.

Middle-Trigger Acquisition

Use middle-trigger acquisition in applications where you want to collect data

before and after an external trigger event. The number of scans stored before

the trigger is specified in M_counter, while the number of scans after the trigger

is specified in SC_counter.

Like pre-trigger mode, the number of stored data can be less than the specified

amount of data (DIV_counter *(M_counter+SC_counter)) if an external trigger

occurs before M scans of data is converted. The M_enable bit in middle-trigger

mode takes the same effect as in pre-trigger mode. If M_enable is set to 1, the

tigger signal will be ignored until the first M scans of data are converted, this

assures user of obtaining M+N scans of data under middle-trigger mode.

However, if M_enable is set to 0, the trigger signal will be accepted at any time.

Fig 14 shows the acquisition timing with M_enable=1.

1 2 ... 47 48 49 50 51 52 53 54 55 56 57 ... 66 67

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ADLINK Technology cPCI-9116 Guida Utente Pagina 52