VTI Instruments Corp.
APPENDIX B
56
Trigger Level
Trigger at Rising Edge
Trigger at Falling Edge
Hysteresis
Figure 4-14: Triggering by Analog Signal
Triggering by External Pulse
The EMX-4250/4350/4380 can receive a trigger from the front panel trigger SMB connector by
enabling the EXT trigger source.
Triggering from Backplane Trigger Line by Other Instruments
The EMX-4250/4350/4380 can receive a trigger from other instruments in the same PXI chassis by
configuring one of PXI trigger lines (PXI0-7) as a trigger source.
Triggering from LAN Events by Other Instruments
The user, or other LXI device, can send a LAN event to trigger the EMX-4250/4350/4380s using
the digitizer/DSA driver. Alternatively, the LAN event can be sent to the EMX-2500 controller
using the platform driver. Upon receiving a LAN trigger event, the EMX-2500 can assert one of the
PXI trigger lines to arm the EMX-4250/4350/4380 (or any other devices within a same chassis).
The former method is more flexible, and is the recommended approach when using all SentinelEX
plugins. It is only recommended to use the Platform method when synchronizing with non-
SentinelEX cards in the same chassis.
Triggering by Stimulus Signal
When the EMX-4250/4350/4380 is used with the EMX-1434 in single DSA driver session, one of
EMX-1434’s DAC channels can be specified as a trigger source. In this configuration, every time
the EMX-1434 generates a signal, it also triggers the EMX-4250/4350/4380 for data acquisition.
D
ATA
R
ETRIEVAL
After a measurement is triggered and at least one record of data (the number of samples specified
by
RecordSize
property in
Sampling
) is available in FIFO buffer, it can be retrieved using the
Read
method in
Measurement
interface or via the
Streaming
method described in the
Data Acquisition
section in this manual. At each trigger event, the number of contiguous records specified by
NumRecordsPerTrigger
are acquired. Multiple records can be read separately or all in once if they
are available in the instrument’s FIFO buffer. The
Read
method in
Measurement
returns at least one
record from all enabled channels.
When the user wishes to acquire continuous samples indefinitely after a single trigger event, set the
NumRecordsPerTrigger
property to 0 (infinite) and set FIFO mode to
Stop
. The data acquisition
stops when the user aborted using the
Abort
method or when the FIFO buffer becomes full (FIFO
overflow). In this setup, the user must retrieve data faster than the ADC data filling into FIFO in
order to avoid FIFO buffer from overflowing.
