Data Translation DT9857, User Manual, Page: 104 / 192

Chapter 5
104
Triggering Acquisition on Multiple Modules
Note: You can synchronize acquisition on multiple DT9857 or DT9857E modules using the
Sync Bus, described on page 105 .
The internal clock on the DT9857 and DT9857E modules when the synchronization mode is
none (see
page 105 ), is derived from the 48 MHz crystal oscillator and provides the timing for
both the analog input and analog output subsystems on the module.
You can start acquisition on multiple modules by connecting all modules to a shared external
trigger input, as shown in
Figure 36 . When triggered, the modules start acquiring data at the
same time.
Using this connection scheme, the measurements of one module may not be synchronous with
the measurements of another module due to logic delays in the clocking and USB circuitry.
Figure 36: Triggering Multiple Modules Using an External Trigger Source
Host PC
DT9857
#1
USB
Port 1
DT9857
#2
USB
Port 2
DT9857
#n
USB
Port n
.
.
.
Device Under
Test
External
Trigger
Inputs
Inputs
Inputs