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Configuring NetDAQ Logger for Windows
Configuring an Instrument
3
3-17
• External Only
A scan is triggered immediately after the external trigger input is pulled
low (active). While the external trigger line remains low, each successive
scan is triggered after Interval 2 elapses since the start of the previous
scan.
• Alarm Only
A scan is triggered when the instrument detects an alarm condition on a
channel being used as an alarm trigger. As long as at least one alarm
trigger channel is in alarm, each successive scan is triggered after Interval
2 has elapsed. The instrument performs background scanning of alarm
trigger channels, according to Interval 5, until it detects an alarm
condition. The Alarm Checking Interval (Interval 3) is configurable in the
netdaq.ini file. Defaults are 1 second (2640A) and 0.1 second (2645A).
When the external trigger is combined with the alarm trigger, scans are
triggered at the Interval 2 rate as long as either the external trigger line is low
or at least one alarm trigger channel is in alarm.
When the interval trigger is combined with the external trigger and/or the
alarm trigger, scans are triggered at the Interval 2 rate when the conditions are
met for the external trigger and/or the alarm trigger, and at the Interval 1 rate
at all other times.
5. Select the slow reading rate for high precision, the fast reading rate for high
speed, or the medium reading for a balance of the two. The actual number of
readings per second depends on the selected functions.
6. Enable Drift Correction to have the instrument automatically correct
measurements for drift due to changes in instrument temperature and
humidity. You can disable Drift Correction to obtain a faster scan rate when
you have set the reading rate to fast, but this may reduce long-term accuracy.
7. Enable Trigger Out (TO) to have the instrument set the rear-panel TO line to
logic low for 125 µs each time a scan starts. Disable Trigger Out if you are not
using it so that the instrument may achieve maximum scanning speeds.
NetDAQ Logger automatically enables the trigger out when an instrument is
the Master of an externally wired group.
8. Enable and enter a value for the duration if you would like NetDAQ Logger to
automatically shut down logging for the instrument after the specified time
has elapsed since the start of logging.