Measurement Computing DaqScan 2000 Series - Manual (Page 53)

DaqScan/2000 Series 898195 Taking Measurements 8-3
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
Synchronous Input Operations
The DaqScan/2000 Series devices allow synchronous scanning and acquisition of Analog Input
[for those models with a P1 connector], Digital Input and Counter Input Data at up to 200 kHz
aggregate scanning rates. When applicable, the Analog Input data can be either main unit
(DaqScan/2001 or DaqScan/2005) or expansion modules from P1-compatible analog input
modules. The Digital Input data can be main unit 8-bit P2 (8255) digital input or from P2
compatible DBK digital input expansion modules.
Analog Input Channels
P1 – Channels 0 through 15 (DaqScan/2001 and DaqScan/2005 only)
DaqScan/2001 and DaqScan/2005 allow analog input configuration of themselves, as well as
for any connected P1 compatible DBK analog input expansion modules.
Channel Selection and Mode Settings
DaqScan/2001 and DaqScan/2005 have P1 connectors that allow for expansion of up to 256
high-speed channels, or 896 TC channels. In regard to system expansion, refer to the DBK
Option Cards & Modules User’s Manual (p/n 457-0905).
Channel Range and Polarity
The analog input channels of DaqScan/2001 and DaqScan/2005 can be programmed for gain
settings of 1, 2, 4, 8, 16, 32, and 64.