API Command Reference Appendix A
A-44 NetScan User’s Manual
start defines the event that is to take place in order for the unit to begin acquiring scans. Thi s event is
referred to as the Start Trigger. When the unit has recognized that a Start Trigger has been enc ount ered, it will
begin acquiring scans at that point. The first of these scans, the Start Trigger scan, will be tim e/date stamped for
later reference. Also, when the Start Trigger is recognized, the Triggered Bit (02) of the Status Byte will be set
and the TRIGGER light on the front panel will turn on.
Setting the start parameter to 0 will disable the acquiring of scan; this may be performed at any time during or
after an acquisition. The start parameter will automatically be set to 0 upon the termination of an acquisition
unless the re-arm flag is set to 1.
Note: If the trigger start event is level or alarm, at least one pre-trigger scan m ust be programmed to initiate
scanning in order for the event to be recognized.
stop defines the event that is to take place in order for the unit to stop acquiring sc ans . This event is referred to
as the Stop Trigger. When the unit has recognized that a Stop Trigger has been encountered, it will stop
acquiring scans at that point (unless post-stop count is defined; see Y c ommand). The last scan collected, the
Stop Trigger scan, will be time/date stamped for later reference. Also, when the Stop Trigger is recognized, the
Trigger Bit (02) of the Status Byte will be cleared and the TRIGGER light on the front panel will turn off.
Setting the stop parameter to 0 will have the same effect as setting the stop parameter to 1 (Stop on Count)
with Post-Stop Count (Y) command set to 0. In both cases, the Start Trigger sc an will be collected and the
acquisition immediately terminated.
re-arm determines if, after the initial acquisition, the acquisiti on s hould be re-enabled automatically. If this
parameter is set, then after the Stop Trigger is recognized and the acquisition term inated a new acquisition (with
the same configuration) will be enabled automatically. In other words, after the termination of the previous
acquisition, the unit will immediately begin another acquisition of the same configuration. Otherwise, if the
parameter is not set, new acquisitions will remain disabled after the initial acquisition has terminated.
sync determines if the Start Trigger should be synchronized with the internal Pre-Trigger Scan Interval (I)
command value. If the Pre-Trigger Count (Y) command is defined, this parameter will be examined to determ ine
if the Start Trigger should be synchronized with the internal Pre-Trigger Timebase Interval. If so, t hen t he Start
Trigger, regardless of what point in time it occurred, will be synchronized with the next occurrence of the Pre-
Trigger Scan Interval “tick.” In other words, if the real Start Trigger occurs between Pre-Trigger Scan Interval
“ticks,” then the acquisition will not begin until the next “tick” of the Pre-Trigger Scan Interval. Otherwise, the
acquisition will begin as soon as the Start Trigger is encountered.
EXAMPLE
PRINT#1, “I12:00:00:0,
00:01:00.0X”
‘ Collect scans once every 12 hours then when Start
Trigger occurs collect them once every minute
PRINT#1, “Y100,10000,0X”
‘ Set pre-trigger count to 100, post-trigger count to 10000
and define no post-stop count
PRINT#1, “T1,7,0,1X”
‘ Start Trigger On (@) command, Stop Trigger on post-
trigger count (10000) and synchronize the Start
Trigger to the pre-trigger timebase interval
PRINT#1, “@X”
‘ Issue Start Trigger (acquisition may begin as much as 12
hours from now because we synchronized with pre-
trigger timebase interval)