Varian 969-4600, Instruction Manual

Page: 30 / 41

TECHNICAL INFORMATION
25 87-900-120-01 (A)
% Helium
The “Tracer gas” selection menu makes it possible to
insert a factor that takes into account the effective
quantity of helium present in the filling gas of the
container under test.
Mix value display
The current setting can be displayed selecting the
“Display Mix.” item
Mix setting
PPM
%
Through the “
Mix setting” item, it is possible to modify
the reference to the concentration used (the factory
setting is 100%). The value can be entered as
percentage of helium in nitrogen (%) or as parts of
helium per million parts of nitrogen (PPM).
NOTES
The rules for entering the values are the same to those
described in the “Use of the menus” paragraph.
Communications
The “Communications” menu permits access to the
settings of the interface board with external devices.
Remote control
Analog Control
RS 232 Control
Setting remote control mode, it is possible to select the
reception channel of the commands from the outside
(analog input / command from serial).
NOTE
Readout of PHD-4 data is always possible on both
channels (RS232 or Analog port) regardless of
selection of “Remote control”.
Baud rate
Using the “Baud rate” command, it is possible to modify
the communication speed on the serial port between
the PHD-4 and external devices. Possible settings are:
1200-2400-4800-9600-19200.
Set-point
The set-point menu makes it possible to manage
enabling of the five set-points of the PHD-4.
NOTES
When enabled, set points 1 – 4 manage the four relays
on the PHD-4 which can be accessed via the rear
connector “I/O-SERIAL”.
Set-points 1,2,3,4
The set-point selected can be enabled accessing the
items of the individual set-points:
Enable
It is also possible to modify the enable value of each
set-point completely independently.
NOTES
The factory-set values are:
Set-point 1 : 10PPM
Set-point 2 : 20PPM
Set-point 3 : 30PPM
Set-point 4 : 50PPM
Safety set-point
The fifth set-point made available by the HID is a set-
point dedicated to protect the PHD-4 against excessive
exposure to high concentrations of helium.
Accessing the “Safety Set-point” item, it is possible (as
for set-points 1-4) to enable operation and to modify the
tripping threshold in the range 2PPM-250PPM in HS
and 100PPM-600PPM in LS (factory settings 100PPM
in HS and 400PPM in LS).
The Safety set-point menu also contains the item: