Instruction Manual IGM402 Hornet
InstruTech
Page 32
CG1 CONT IG
This allows the use of the pressure measurement from CG1 to automatically turn the selected filament on
and off.
Pin 1 of the ANALOG connector must be connected to Pin 2 of the ANALOG connector and
emission current must be set to 100 μA for this function to work. To operate the IG at an emission current
of 4 mA, see ‘2)’ below. The filament will be turned on at the
100UA TRN ON
setting when in the
CG1
CONT IG
mode.
The on/off control of the IG filament using the pressure measured by CG1 can be set under
two different scenarios:
1)
If the ion gauge emission current is set to 100 µA, the ion gauge filament will turn on when the pressure
measured from CG1 drops below the value programmed in the
100UA TRN ON
submenu of the
SETUP
UNIT
menu. The ion gauge filament will turn off when the pressure measured from CG1 rises above the
pressure value programmed for the
100UA TRN ON
setting.
2)
If the ion gauge emission current is set to 4 mA, the ion gauge filament will turn on when the pressure
measured from CG1 drops below 1.00 x 10
-3
Torr. The ion gauge filament will turn off when the
pressure measured from CG1 rises above 1.00 x 10
-3
Torr.
Note -
To turn the IG filament off manually when
CG1 CONT IG
is selected, pin 1 of the ANALOG
connector must be disconnected from pin 2 of the same connector. This is the case only when filament
turn off is required before the pressure measured by CG1 rises above the maximum of 5.00 x 10
-2
Torr
for the 100 µA emission current setting and 1.00 x 10
-3
Torr for the 4 mA emission current setting.
It is
highly recommended that PIN 1 of the Analog connector is wired in such a way that it can be connected
to pin 2 of the Analog connector, but that connection can be opened to manually turn off the IG. This
will allow the user to override the CG turning on the IG.
Use of a manual switch which can be easily
accessed by the user should be considered.
The IG
will only turn OFF when the connection between
pins 1 and 2 of the ANALOG connector is open circuit and the main pressure display screen is active. If
the display screen is in one of the programming menus the manual switch is ignored and the IG will not
turn OFF even if the switch between pins 1 and 2 is open circuit.
When
CG1 CONT IG
is selected, the
emission current
and
degas
will operate using Digital Inputs as
described in the previous section (
-
IG CNTL, DIGI/RS485
)
as defined by the ANALOG connector pin-out
in
section 3.3.2.1
. For example, the default emission current setting for the IG when in the
CG1 CONT IG
mode of operation is 100 μA. If it is desired to operate the IG with an emission current of 4 mA, then it
will be necessary to provide capability to switch the emission current select pin (ANALOG connector
contact 8) to power ground (circuit common) available at pin 2 of the ANALOG (DE-9P) connector of the
IGM402 while operating in the
CG1 CNTL IG
control mode.
