Lake Shore Model 340 Temperature Controller User’s Manual
4-8
Front Panel Operation
4.5.6 Heater Output Display Units
The
CONTROL DISPLAY FORMAT
screen is also the place to select whether heater output is shown as
POWER
or
CURRENT
. This setting will impact the heater output seen in the normal display and which units
are used for the manual output (
MOut
) display. If current is selected, the heater output and range will appear
as
20% @ 100 W
to indicate 20% output current for the selected 100 watt range. If power is selected for the
same output, the heater output and range would appear as
4% of 100W
to indicate 4% output power for the
selected 100 watt range.
To change the heater display units, press the
Display Format
key, then press the
More
key until you see the
CONTROL DISPLAY FORMAT
screen. Press the
Next Setting
key until the
Heat Display
line is highlighted,
then use the
s
or
t
key to select
Current
or
Power
. Press the
Enter
or
Next Setting
key to continue with
other settings. Press the
Save Screen
key to store the changes. The default setting is Current.
4.5.7 Display
Contrast
The Model 340 has a high contrast, LCD display with a bright backlight. The factory contrast setting is good
for most applications, but it will need to be changed for arrangements of equipment that put the Model 340
well above or below eye level. Display contrast can be set to a value between 0 an 100. Please note that
changing contrast has no effect on the display backlight.
To change display contrast, press the
Display Format
key then press the
More
key until the
Misc. Display
Format
screen is displayed. Press the
Next Setting
key until the
Contrast
line is highlighted, then use the
s
or
t
key to adjust contrast. The contrast will change as the parameter is being set, so adjustments should
be made with the operator and instrument in their normal positions. Press the
Enter
or
Next Setting
key to
continue with other settings. Press the
Save Screen
key to store the changes in the Model 340. The default
setting is 50.
4.5.8 Display Backlight On/Off
The Model 340 display used a florescent tube as a backlight. The backlight is powered with a high voltage
supply operating at 30 kHz. Some experiments are sensitive to noise in the frequency range of 30 kHz, so the
backlight power supply can be turned off. Please note that the display is unreadable when the backlight is off.
To turn the display backlight off, press the
Display Format
key, then press the
More
key to show the
MISC.
DISPLAY FORMAT
screen. Press the
Next Setting
key until the line for backlight is highlighted, then use the
s
or
t
key to turn the backlight off. Press the
Save Screen
key to store the changes. Default setting is On.
To turn the display backlight back on, press any key on the keypad.
4.5.9 Locking
the
Keypad
The Model 340 has a keypad lock feature to prevent accidental changes to instrument parameters and
minimize the disturbances of curious onlookers. A simple 3 number sequence is the code needed to lock and
unlock the keypad. The factory default code is
123
and it can only be changed using a computer interface.
To lock or unlock the keypad, press the
Display Format
key then press the
More
key to show the
Misc.
Display Format
screen. Press the
Next Setting
key until
Lock
is highlighted, then use the
s
or
t
key to
toggle the lock setting. Press the
Enter
key. A small setting window will appear for entering a three digit
number code. Use the number keys to enter the code, then press the
Enter
key. Press the
Save Screen
key
to store the lock status in the Model 340. The default setting is unlocked, code
123
.
When the keypad is locked, you can still see values for the various parameters, you just cannot change them.
The only front panel keys that are active when the keypad is locked are the Heater Off and Alarm Reset keys.
4.6 DEFAULT
VALUES
It is sometimes necessary to reset instrument parameters to their factory default values. These values can be
cleared without affecting instrument calibration.
To reset the Model 340 parameters to factory default values, press the
Options
key then press the
More
key
until the Revision Information screen is displayed. Up the
s
or
t
key to change the Set Defaults setting to
Yes, then press the
Enter
key. Press the
Save Screen
key to complete the action. The Model 340 will then
restart using the factory default values.