LI-COR LI-6400, Manual

Page: 219 / 846

Environmental Control
OpenÕs Control Manager
Using the LI-6400 7-5
sequences of an inactive control manager are minor, at least over short time
periods. Some controls are implemented in hardware (such as block temper-
ature control and null balance water vapor control), so even without the con-
trol manager, they will still actively track. The others will simply have stable
targets that wonÕt be adjusted to account for changing temperature. Specifics
can be found in the ISR descriptions for each control described below.
Variable Targets
Any control mode whose target entry box includes a pound sign (#) after the
default label can have a variable target, rather than a fixed value target. For
example, you may wish to maintain a relative chamber humidity that is the
same as the humidity measured with an external humidity sensor. Rather than
entering a number for the target, enter a pound sign
#
and press
enter
. You will be shown a list of system and user defined variables,
from which you can pick the quantity that is to be tracked.
Alternatively, if you know the ID number for the system variable or user vari-
able, you can enter it directly and bypass the menu selection.
#-13
(Variable number -13 is the external quantum sensor, for example.) When a
variable target is specified, the target is updated every 30 seconds, but only
while the control manager is active.
■ ■ ■ ■
Example: Tracking External Humidity
Suppose we want to make chamber humidity track a value provided by user
channel #1001 named
xtrnRH . Once this is defined appropriately in the Com-
pute List File (Chapter 15), we can press F2 to select the flow/humidity con-
trol, press
R
for RH_sample control, and type
#1001 enter
(Figure 7-4). Or,
you could just enter # and pick xtrnRH from the menu.
50 % #
RH_sample
#1001
Figure 7-4. Instead of entering a fixed target value, you can specify a vari-
able, system or user. The target value comes from this variable, and is up-
dated every 30 seconds.