ADLINK PXI-2022 - Manual (Page 48)

40 Function Block and Operation Theory
4.7 Synchronizing Multiple Modules
SSI (System Synchronization Interface) provides the DAQ timing
synchronization between multiple cards. In PXI-2020/2022 series,
we designed 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 sig-
nals are designed for card synchronization only, not for external
devices.
In PXI form factor, we utilize the PXI trigger bus built on the PXI
backplane to provide the necessary timing signal connections. All
the SSI signals are routed to the P2 connector. No additional cable
is needed. For detailed information of the PXI specifications,
please refer to PXI specification Re-vision 2.0 from PXI System
Alliance (www.pxisa.org).
The eight interconnected lines on PXI backplane named as PXI
Trigger Bus[0:7] provide a flexible interface for multiple modules
synchronization. The PXI-2020/2022 utilizes the PXI Trigger
Bus[0:7] as the System Synchronization Interface (SSI). By pro-
viding flexible routing of timebase clock and trigger signals onto
PXI Trigger Bus, the PXI-2020/2022 makes the synchronization
be-tween multiple modules easy and simple. The bi-directional
SSI I/Os provide a flexible connection between modules, which
allows one SSI master PXI-2020/2022 to output the SSI signals to
other slaves modules to receive the signals. Table 4-4 lists the
summary of SSI timing signals and the functionalities. Figure 4-15
shows the architecture of SSI. Note that it’s not allowed to route
different signals onto the same trigger bus line.
SSI Timing Signal Functionality
SSI_TIMEBASE
SSI master: send the TIMEBASE out
SSI slave: accept the SSI_TIMEBASE to replace the internal TIME-
BASE signal.
Note: Affects A/D and 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.
Table 4-4: SSI Timing