Programming and Operation
3-38
P/N 8040406
C
HELIX TECHNOLOGY CORPORATION
-
TI
CRYOGENICS
Parameter Lock
The eighth parameter of the SERVICE function prevents an unauthorized
user from accessing all programmable REGEN parameters and relay
setpoints. When an attempt is made to change a programmable setpoint
with Parameter Lock ON, the CHANGES LOCKED message is displayed
as shown in Figure 3-35. All parameters which can be turned ON or OFF,
including Regeneration, are still accessible with Parameter Lock turned
ON.
Figure 3-35: Parameter Lock ON Display
Zero Auxiliary Thermocouple
The ninth parameter of the SERVICE function, as shown in Figure 3-36,
resets the auxiliary thermocouple gauge to zero. The auxiliary
thermocouple gauge reading is displayed until the gauge is set to zero.
NOTE: The auxiliary thermocouple gauge must be turned ON and under a
vacuum of less than 10
-4
torr (less than 1 micron) before this parameter can
be used. Any attempt to zero the gauge at a pressure above 30 microns, or
when the gauge is turned OFF, results in a calibration failure.
Figure 3-36: Zero Auxiliary Thermocouple Display
Last
Next
Clear
MONITOR
REGEN
SERVICE
CONTROL
RELAYS
HELP
oo
ON
-BOARD
®
Enter
1
2
3
4
5
6
7
8
9
-
0
.
PARAM LOCK OFF
Last
Next
Clear
MONITOR
REGEN
SERVICE
CONTROL
RELAYS
HELP
oo
ON
-BOARD
®
Enter
1
2
3
4
5
6
7
8
9
-
0
.
ZERO AUX TC