Measurement Computing TempScan/1100 - Manual (Page 74)

4-16 System Configuration 879596 TempScan / MultiScan User's Manual
To enable the gap-free acquisition with two timebases, you must perform the following:
• Specify the two trigger events – the Trigger (trigger start event) and the Stop (trigger stop event) – via
the Set Trigger Configuration ( T ) command.
• Set the two timebase intervals – the normal and the acquisition scan intervals – via the Set Scan
Interval ( I ) command.
• Set the Pre-Trigger count to
-1 , via the pre parameter of the Set Counts ( Y ) command. If more than
one transition cycle is desired, enable the Auto Re-arm flag of the Set Trigger Configuration ( T )
command to allow each transition cycle to be stored in its own Trigger Block within the buffer.
Using this method, continuous data may be collected as long as the application program can read data out
of the Acquisition Buffer before the buffer overruns. If the buffer overruns, the data read may not be
continuous.
Trigger Configuration
Trigger Start & Stop Events
The programmed system events are the driving force behind any acquisition. For an acquisition to take
place, the Set Trigger Configuration (
T ) command is used as the central command to assign the following
events to the TempScan/1100 or MultiScan/1200 unit: The Trigger (trigger start event) and the Stop
(trigger stop event). The Trigger and Stop may also be assigned different trigger sources. In addition, the
Set Trigger Configuration (
T ) command also determines whether or not, after the initial acquisition, the
acquisition will be re-enabled automatically, and whether or not the Trigger (trigger start event) should be
synchronized with the Pre-Trigger scan interval.
Upon the execution of this command, the unit will enter acquisition mode, and the TRIGGER LED
indicator on the front panel will flash. If Pre-Trigger scans have been configured via the Set Counts (
Y )
command, then the sampling for Pre-Trigger data will begin at this time. Specifically, the Set Trigger
Configuration (
T ) command is used to set the following parameters:
• Trigger (trigger start event): This parameter is the event that is to take place in order for the unit to
begin acquiring scans. When the unit detects a Trigger, it will stop acquiring Pre-Trigger scans (if
configured), and begin acquiring Post-Trigger scans at that point. The first of these Post-Trigger
scans, the Trigger scan, will be Time/Date stamped for later reference, such as in a response to the
following User Status (
U ) command query: U6 – Query the Buffer Status String. Also, when the
Trigger is detected, the Triggered Bit (Bit 1) of the Status Byte Register ( STB ) will be set and the
TRIGGER LED indicator on the front panel will turn on.
• Stop (trigger stop event): This parameter is the event that is to take place in order for the unit to stop
acquiring scans. When the unit detects a Stop, it will stop acquiring Post-Trigger scans at that point,
unless Post-Stop scans are defined via the Set Counts (
Y ) command. The last of these Post-Trigger
scans, the Stop scan, will be Time/Date stamped for later reference, such as in a response to the
following User Status (
U ) command query: U6 – Query the Buffer Status String. Also, when the Stop
is recognized, the Triggered Bit (Bit 1) of the Status Byte Register ( STB ) will be cleared and the
TRIGGER LED indicator on the front panel will turn off.