Models 947, 948 and 960 Leak Detectors Operations and Service Manual
3-3
3.2 Initial System Parameter Setup
The 947/948/960 performs functions and tests based upon parameter values. Some
parameters are entered and set when the system is assembled and tested. Some parameters
are calculated and change automatically during power up, Calibrate, or Zero functions.
Other parameters are changed when a change is made to the physical system, such as when
a thermocouple gauge, ion source or preamplifier is changed. These parameters are set as a
function of the physical configuration and sensitivity needs.
Several parameters relating to the operation and performance are stored in EPROM in the
control unit. The information for these parameters is not lost when the power is shut down.
Parameters can be viewed and changed through commands entered via the service pendant
or host computer.
Section 3.2.1, “Parameters and Operating Modes” explains the parameters and what
happens during the related function.
3.2.1 Parameters and Operating Modes
The parameters and operating modes work together to perform leak detection, and the
parameters that are entered determine the type of test and sensitivity of testing performed.
The discussion below includes an explanation of what the parameter or function means. For
additional information on how to set a parameter or select a function, refer to Section 3.3,
“Start-Up” on page 3-9 and Appendix A, “Service Pendant Keypad Functions”, or if the
optional rear panel interface is installed, Section C, “Communications Protocol”.
RANGE
The 947/948/960 automatically sets the Range equal to the
exponent of the least sensitive range of the leak detector,
depending on the sensitivity of the vacuum system.
AUTO-RANGE and
MANUAL RANGE
Auto-Ranging causes the leak detector to automatically
change the leak rate exponent and mode to keep the leak
rate reading on scale.
Manual Range is used to force the 947/948/960 to display a
leak rate in only one decade (the exponent never changes).
This feature is useful when the test operator is only
concerned with monitoring the leak rate measurement
within a single decade. Set the Leak Rate Range Mode to
MAN and use the SMALLER or LARGER buttons to change
the range.
RANGE STOP
The RANGE STOP feature configures the 947/948/960 so
that it only auto-ranges down to the pre-selected decade
entered in the range stop variable field. For example, if
RANGE STOP is enabled and set to
−
07, then the most
sensitive range that the leak detector displays is 10
−
7
.
