User guide

14 Advanced User Guide
Run Time Programming
Run time programming allows certain setpoints to change
automatically during a run as a function of the chromatographic
run time. Thus an event that is programmed to occur at
2 minutes will occur 2 minutes after every injection.
Its uses include:
• Controlling column switching or other valves
• Changing signal definition, zero, or range
• Controlling an auxiliary pressure channel
• Changing polarity of a thermal conductivity detector (TCD)
• Turning the hydrogen flow to a nitrogen- phosphorus
detector (NPD) on or off
• Pausing (freezing) and resuming a signal value
The changes are entered into a run table that specifies the
setpoint to be changed, the time for the change, and the new
value. At the end of the chromatographic run, most setpoints
changed by a run time table are returned to their original
values.
Valves can be run time programmed but are not restored to
their starting position at the end of the run. You must program
the reset operation in the run table if this action is desired. See
“From the run or clock time tables” on page 345.
Using run time events
The [Run Table] key is used to program timed events.
You can control the following events during a run.
• Valves (1- 8)
• Multiposition valve
• Signal type (see “Signal Types” on page 369)
• Analog signal zero and range
• Digital signal zero and baseline level shifts (see “Digital zero”
on page 374)
• Auxiliary pressures (1 through 9)
• TCD negative polarity (on/off)
• NPD H
2
flow (on/off)
• Pausing (freezing) and resuming a signal value