Omega Vehicle Security 1400 User Manual
Appendix B
Configuration Aspects for Programmers
ChartScan User’s Manual
B-13
Post-Trigger State
The Post-Trigger state is the period between the occurrence of the trigger event and the occurrence of the stop
event. While the unit is in this state the TRIGGER LED will be on and the alarms and their associated outputs
will be updated at the post-trigger scan rate.
event. While the unit is in this state the TRIGGER LED will be on and the alarms and their associated outputs
will be updated at the post-trigger scan rate.
During the Post-Trigger state the unit will collect Post-Trigger data at the rate specified by the acquisition scan
interval specified by the Scan Interval (
interval specified by the Scan Interval (
I
) command. Post-Trigger scans will be collected at this rate until the
stop event occurs. The number of scans collected during the Post-Trigger state is not restricted by the internal
buffer size. ChartScan can collect scans in the post-trigger state indefinitely if the controlling computer is
capable of reading data out of the acquisition buffer fast enough to prevent a buffer overrun.
buffer size. ChartScan can collect scans in the post-trigger state indefinitely if the controlling computer is
capable of reading data out of the acquisition buffer fast enough to prevent a buffer overrun.
The Post-Trigger state may be detected by querying the Triggered Bit of the Status Byte (STB) Register and the
Stopped Bit of the Event Status Register (ESR). ChartScan is in the Post-Trigger state if and only if the
Triggered Bit of the STB is set and the Stopped Bit of the ESR is not set. The unit will exit the Post-Trigger
state when the stop event occurs.
Stopped Bit of the Event Status Register (ESR). ChartScan is in the Post-Trigger state if and only if the
Triggered Bit of the STB is set and the Stopped Bit of the ESR is not set. The unit will exit the Post-Trigger
state when the stop event occurs.
Post-Stop State
The Post-Stop state is the period between the occurrence of the stop event and the completion of the acquisition.
While the unit is in this state the TRIGGER LED will be on and the alarms and their associated outputs will be
updated at the post-stop scan rate.
While the unit is in this state the TRIGGER LED will be on and the alarms and their associated outputs will be
updated at the post-stop scan rate.
ChartScan will only enter this state when a non-zero value of the post-stop count parameter of the Set Counts (
Y
)
command has been specified. If this is the case, upon the occurrence of the stop event the unit will enter the
Post-Stop state and collect the specified number of post-stop scans.
When the specified number of post-stop scans have been collected, the unit will terminate the current acquisition
and return to a non-acquiring state. If, however, the post-stop count parameter of the Set Counts (
Post-Stop state and collect the specified number of post-stop scans.
When the specified number of post-stop scans have been collected, the unit will terminate the current acquisition
and return to a non-acquiring state. If, however, the post-stop count parameter of the Set Counts (
Y
) command is
zero the unit will return immediately to a non-acquiring state upon the occurrence of the stop event (unless the
Auto-Rearm feature is used).
Auto-Rearm feature is used).
The Post-Stop state may be detected by querying the Stopped and the Acquisition Complete bits of the Event
Status Register (ESR). ChartScan is in the Post-Stop state if and only if the Stopped Bit of the ESR is set and
the Acquisition Complete Bit of the ESR is not set. The unit will exit the Post-Stop state when the specified
number of post-stop scans have been collected. When this occurs the Acquisition Complete Bit of the ESR will
be set and the unit will return to a non-acquiring state (unless the Auto-Rearm feature is used).
Status Register (ESR). ChartScan is in the Post-Stop state if and only if the Stopped Bit of the ESR is set and
the Acquisition Complete Bit of the ESR is not set. The unit will exit the Post-Stop state when the specified
number of post-stop scans have been collected. When this occurs the Acquisition Complete Bit of the ESR will
be set and the unit will return to a non-acquiring state (unless the Auto-Rearm feature is used).
Trigger and Stop Events
The programmed system events are the driving force behind any acquisition. The trigger point (also referred to
trigger event) signals the end of the pre-trigger and the beginning of the post-trigger; the stop event signals the
end of the post-trigger and the beginning of the post-stop.
trigger event) signals the end of the pre-trigger and the beginning of the post-trigger; the stop event signals the
end of the post-trigger and the beginning of the post-stop.
In addition to the pre-trigger (normal) scan interval, a secondary post-trigger (acquisition) scan interval can be
assigned. This would allow scans during the post-trigger and post-stop states to be collected faster or slower
than those in the pre-trigger. One application for this secondary scan interval is when events after the trigger
require faster sampling than those before the trigger, such as during alarm conditions.
ChartScan can be configured to start data acquisition on one of many trigger sources. The Trigger
Configuration (
assigned. This would allow scans during the post-trigger and post-stop states to be collected faster or slower
than those in the pre-trigger. One application for this secondary scan interval is when events after the trigger
require faster sampling than those before the trigger, such as during alarm conditions.
ChartScan can be configured to start data acquisition on one of many trigger sources. The Trigger
Configuration (
T
) command is used to set: the source of the trigger (GET, Talk, etc.), the trigger start and stop
event, a pre-trigger count and/or post-stop count if used, the direction of the trigger source level if used (rising
or falling edge), and whether the Auto-Rearm flag is enabled.
or falling edge), and whether the Auto-Rearm flag is enabled.
If the Auto-Rearm feature is in use, the unit will immediately begin looking for another trigger event once a stop
event and post-stop event is detected. If the feature is not in use, a
event and post-stop event is detected. If the feature is not in use, a
T
command must be issued after a stop event
before the unit can begin looking for a trigger. However, using Auto-Rearm does not allow the user to change
the trigger configuration between triggers; the initial configuration will be used until Auto-Rearm is disabled.
To disable Auto-Rearm, a
the trigger configuration between triggers; the initial configuration will be used until Auto-Rearm is disabled.
To disable Auto-Rearm, a
T
command must be issued with the flag set to zero. Data will still be available after
the
T
command is issued. Refer to the Command Reference section for details.