Measurement Computing DaqBook 2000 Series - Manual (Page 65)

Pre- and Post-Triggering Modes. Six modes of pre- and post-triggering are supported, providing a wide
variety of options to accommodate any measurement requirement. When using pre-trigger, the user must
use software-based triggering to initiate an acquisition.
•
No pre-trigger, post-trigger stop event.
This, the simplest of modes, acquires data upon
receipt of the trigger, and stops acquiring upon receipt of the stop-trigger event.
•
Fixed pre-trigger with post-trigger stop event.
In this mode, the user specifies the number of
pre-trigger readings to be acquired, after which, acquisition continues until a stop-trigger
event occurs.
•
No pre-trigger, infinite post-trigger.
No pre-trigger data is acquired in this mode. Instead,
data is acquired beginning with the trigger event, and is terminated when the operator issues a
command to halt the acquisition.
•
Fixed pre-trigger with infinite post-trigger
. The user specifies the amount of pre-trigger data
to acquire, after which the system continues to acquire data until the program issues a
command to halt acquisition.
•
Variable pre-trigger with post trigger stop event
(driver support only). Unlike the previous
pre-trigger modes, this mode does not have to satisfy the pre-trigger number of readings
before recognizing the trigger event. Thus the number of pre-trigger readings acquired is
variable and dependent on the time of the trigger event relative to the start. In this mode, data
continues to be acquired until the stop trigger event is detected.
•
Variable pre-trigger with infinite post trigger
(driver support only). This is similar to the
mode just described, except that the acquisition is terminated upon receipt of a command
from the program.
•
Stop Trigger
. Any of the software trigger modes described above can be used to stop an
acquisition. Thus an acquisition can be programmed to begin on one event, such as a
temperature level, and then stopped on another, such as a digital pattern event.
Synchronous I/O Operations
Synchronizing Multiple Units
DaqBook/2000 and DaqOEM/2000 Series devices can be
synchronized to each other via their SYNC ports. Each
unit has two identical SYNC ports. Either, or both, SYNC
ports can be used to connect to the units via SYNC cables,
CA-74-1 or CA-74-5 (1-foot or 5-foot cables,
respectively). The units can be scan-synchronized and
triggered from any other SYNC-connected unit.
Synchronization Concept Block Diagram
The preceding diagram shows how a DaqBook can input or output synchronization timing and trigger
events on either SYNC connector. A more detailed block diagram follows shortly.
SYNC cables are not to exceed a total combined length of 15 feet (4.57 m).
Reference Note: The SYNC features are programmable via software. For detailed
information see the Using Multiple Devices and the daqAdcSetClockSource sections of
the Programmer’s Manual (p/n 1008-0901).
PDF NOTE:
During software installation, Adobe ® PDF versions of user manuals automatically install onto
your hard drive as a part of product support. The default location is in the Programs group,
which can be accessed from the Windows Desktop. Refer to the PDF documentation for
details regarding both hardware and software.
DaqBook/2000 and DaqOEM/2000 Series 898695 Taking Measurements 8-3