User`s guide

Operation Theory

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EXTDTRIG and EXTWFTRIG

EXTDTRIG and EXTWFTRIG are dedicated digital trigger input sig-

nals for A/D and D/A operations respectively. Please refer to section

4.5.3 for detailed descriptions.

EXTTIMEBASE

When applications need specific sampling frequency or update rate that

the card cannot generate from its internal TIMEBASE, the 40MHz clock,

then users can utilize the EXTTIMEBASE with internal counters to achieve

the specific timing intervals for the A/D operations.

AFI[0]

Alternatively, users can also directly apply an external A/D conversion

signal to replace the internal ADCONV signal. This is another way to

achieve customized sampling frequencies. The external ADCONV signal

can only be inputted from the AFI[0]. As section 4.1 describes, the

SI_counter triggers the generation of the A/D conversion signal, ADCONV,

but when using the AFI[0] to replace the internal ADCONV signal, then the

SI_counter and the internally generated SCAN_START will not be effective.

By controlling the ADCONV externally, users can sample the data ac-

cording to external events. In this mode, the Trigger signal and trigger

mode settings will are not available.

AFI[0] can also be used as SCAN_START signal for A/D operations.

Please refer to sections 4.1 and 4.5.1 for detailed descriptions of the

SCAN_START signal. When using external signal (AFI[0]) to replace the

internal SCAN_START signal, the pulse width of the AFI[0] must be greater

than two times of the period of Timebase. Note that the AFI[0] is a

multi-purpose input, and it can only be utilized for one function at any one

time.

AFI[1]

(for DAQ-2214)

Regarding the D/A operations, users could directly input the external D/A

update signal to replace the internal DAWR signal. This is another way to

achieve customized D/A update rates. The external DAWR signal can only

be inputted from the AFI[1]. Note that the AFI[1] is a multi-purpose input,

and it can only be utilized for one function at any one time. AFI[1] currently

only has one function. ADLINK reserves it for future development.