GFS2102™ OPERATION AND MAINTENANCE MANUAL
© 2007 DH Instruments, a Fluke Company
Page 132
Table 54.
GFS Configuration
Editor
[System]
Tab Fields
FEATURE
DESCRIPTION
Output display
refresh rate (ms)
(required numeric
entry)
The time in milliseconds between screen updates on the GFS run display. Using a time
gap between display updates helps to minimize system flicker at higher flow rates.
Balance RS232 poll
interval (ms)
(required numeric
entry)
The time in milliseconds between LCM balance samples. The LCM sends commands to
read the balance at the time interval regardless of the flow rate or other sampling criteria.
100ms is the recommended setting. Do not enter a value below 100ms, the LCM is not
capable of sampling faster than this.
Minimum mass
change per GFS
sample
(required numeric
entry)
Indicates the minimum change in the balance indication at a given flow rate required for a
GFS sample. The limit allows
GFS Tools
to automatically limit the number of samples as
the flow rate changes. At very low flow it is not possible to distinguish between short term
drift of the balance and an actual mass change as a result of flow. For this reason it is
important to take samples only when a change in mass should have occurred as a result
in change in flow.
Since all samples are logged in the SDF file, the value entered determines the
approximate number of samples logged in the file.
For example a flow rate of 10
requires 5s to deplete 0.001g of N2. A
mimimum mass change entry of 0.002 results in a GFS sample every 10s. A value of
0.001g causes a flow rate of 1 slm to result in a GFS sample every 0.005s, but with the
<Balance RS232 poll interval>
set to 100ms would limit this to a sample every 0.1s. If
the sample time is less than the
<Balance RS232 poll interval>
a sample is taken with
every balance update. (see section 5.7.11, Sample Rate)
Number of rolling
average flow
samples
(required numeric
entry)
The number of flow samples to include in the rolling average flow of the GFS. The
samples are added to the rolling average at the rate determined by the
<Minimum mass
change per GFS sample>
entry.
Enter 1 to disable the rolling average flow. In this case the
<Flow>
and the
<Rolling Avg
Flow>
on the
GFS Diagnostics
run screen are the same.
Number of GFS
samples per rolling
mass best fit
(required numeric
entry)
The number of GFS samples to include in the rolling mass best fit of the GFS. After the
defined number of samples are taken, each new balance sample causes the end balance
sample to be removed from the fit.
Enter 1 to disable the rolling average (not recommended). In this case the software will
use instantaneous mass values instead of predicted values.
Maximum number
of balance samples
in rolling mass fit
(required numeric
entry)
The number of mass samples to include in the rolling mass best fit of the GFS. The
samples are added to the rolling average at the rate determined by the
<Minimum mass
change per GFS sample>
entry.
Enter 1 to disable the rolling average flow. In this case the
<Flow>
and the
<Rolling Avg
Flow>
on the
GFS Diagnostics
run screen are the same.
Automate external
isolation valve
(required check box
selection)
Select this option to use the LCM driver 4 to automate the flow isolation valve. The
isolation valve is located in the GFS sidewall column between the GFS Reference Gas
Cylinder and the connection to the DUT.
GFS Tools
activates this valve to force zero flow
for leak test and when a test is complete.