DH Instruments PPC2+, Manual

Page: 46 / 166

PPC2+™ Operation and Maintenance Manual
©2001 DH Instruments, Inc.
Page 38
Selecting <1Yes> causes the sequence to abort and returns to the main
run screen. Selecting <2No> causes the sequence to resume where it left off.
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3.2.6 CUSTOM CONTROL
m
PURPOSE
To customize the control parameters of the current automated pressure control mode for
the current range.
m
PRINCIPLE
Automated pressure control and the associated pressure Ready (<*>)/Not Ready (<
↑
> or
<
↓
>) condition are characterized by hold limit and stability limit parameters which
determine how PPC2+ will control and under what conditions a Ready (<*>) indication will
occur (see Sections 3.1.2.3 and 3.1.2.4).
PPC2+ provides system default values for the hold limit and stability limit parameters for
each range which have been determined to be those most suitable for the typical user to
operate within PPC2+ pressure control and measurement specifications. The default
parameters are automatically set each time the control mode is selected using the
[CONTROL] function key (see Table 7).
The CUSTOM CONTROL function allows the hold and stability limit parameters to be
adjusted by the user. This can be used to increase control speed (time to Ready (<*>)),
usually by decreasing control precision, or to increase precision which usually decreases
control speed (see Section 3.1.2.4). For example, changing the dynamic pressure control
hold limit from its default value of ± 0.005 % FS of the current range to ± 0.01 % FS of the
current range will decrease the time required to set a pressure (achieve a Ready (<*>)
condition) since the limit in which the pressure must be set has increased by a factor of
two but it will also increase by a factor of two the maximum possible control error included
when Ready (<*>) is indicated.
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