User`s guide

Operation Theory • 63
AFI[1]
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.
4.6.3 System Synchronization Interface
SSI (System Synchronization Interface) provides the DAQ timing syn-
chronization between multiple cards. In DAQ/PXI-22XX series, we de-
signed a bi-directional SSI I/O to provide flexible connection between cards
and allow one SSI master to output the signal and up to three slaves to
receive the SSI signal. Note that the SSI signals are designed for card
synchronization only, not for external devices.
SSI timing signal Functionality
SSI_TIMEBASE
SSI master: send the TIMEBASE out
SSI slave: accept the SSI_TIMEBASE to replace the internal
TIMEBASE signal.
Note: Affects on both A/D and D/A operations
SSI_AD_TRIG
SSI master: send the internal AD_TRIG out
SSI slave: accept the SSI_AD_TRIG as the digital trigger
signal.
SSI_ADCONV
SSI master: send the ADCONV out
SSI slave: accept the SSI_ADCONV to replace the internal
ADCONV signal.
SSI_SCAN_START
SSI master: send the SCAN_START out
SSI slave: accept the SSI_SCAN_START to replace the
internal SCAN_START signal.
SSI_DA_TRIG
SSI master: send the DA_TRIG out.
SSI slave: accept the SSI_DA_TRIG as the digital trigger
signal.
SSI_DAWR
SSI master: send the DAWR out.
SSI slave: accept the SSI_DAWR to replace the internal
DAWR signal.
Table 16: Summary of SSI timing signals and the corresponding func-
tionalities as the master or slave