Data Translation DT9857, Руководство пользователя, Страница: 109 / 192

Principles of Operation
109
If you want to synchronize all the analog input subsystems of multiple DT9857E modules, use
software to specify the synchronization mode of the A/D subsystem of each module as a
master or slave. If you want to synchronize the analog output subsystems of multiple
DT9857E modules, specify the synchronization mode of the D/A subsystem of each module
as master or slave. Use a synchronization mode of none (the default value) if you do not want
to synchronize the subsystem.
Notes: The analog input subsystems are synchronized with each other and the analog output
subsystems are synchronized with each other. However, the analog inputs and analog
outputs are not guaranteed to be synchronized with each other; but, they will correlate with
each other from run to run.
The synchronization modes of the A/D and D/A subsystems are independent from each
other; however, the same device cannot have one subsystem configured as the master and the
other subsystem configured as the slave or an error will be reported.
When configured as a master, the Sync Bus connector outputs trigger and clock signals. When
configured as a slave, the Sync Bus connector accepts trigger and clock signals from the
master; the start trigger source on the slave module in is ignored in this configuration since the
Sync Bus is used as the start trigger. When configured as none (the default mode), the
DT9857E module uses the 48 MHz reference clock instead of the Sync Bus connector. The
synchronization mode remains set until changed or until the application exits.
Figure 40 shows how to connect a maximum of 16 DT9857E modules to synchronize all the
analog input channels.
Note: The following diagrams show USB 3.0 hubs connected to the host computer.
However, if you are using fewer modules, you can connect modules directly to the USB 2.0 or
USB 3.0 ports of your host computer as long as your host computer provides enough USB
ports.