Page 5 Model 421508 Version 1.0 October 2002
REL Relative key
Press the REL key to enter the Relative mode. The meter will now store the displayed
reading (main display) as a reference value and display ‘REL’. All subsequent readings will
now display less the stored reference value. Press the REL key again to exit the relative
mode. Note that the Relative reference value can also be entered manually (see the ‘SET
Key’ paragraph below). The Relative mode is also a useful zeroing function. Note that the
reference value cannot exceed ±3000.0 counts.
Hi/Lo LIMITS key (Main display only)
Press the Hi/Lo LIMITS key to enter the Hi/Lo Limits comparative mode ("LIMIT" will be
displayed on the LCD). When the measured temperature is higher than the High Limit (or
lower than the Low Limit), the alarm beeper emits a tone and "Hi" “or “Lo” is displayed.
Note: The tones for High and Low Alarms are different; the High Alarm tone is continuous
while the Low Alarm tone is pulsed. Use the SET key to program the temperature limits as
explained in the next paragraph. Press the Hi/Lo LIMIT key again to exit the Hi/Lo LIMIT
mode. In this mode the automatic power-off feature is disabled along with the following
keys: REL, HOLD, & MIN MAX.
SET Key (Setting Relative Value, High / Low Alarm Limits, and the Timer)
Follow the steps a. through c. below for programming any or all of the SET parameters.
Use the overlay second-function keys (- 0 through 9 and ENTER) when entering numbers.
For negative numbers, press the (- 0) key after the number has been entered. The ENTER
key is used to enter the programmed data and queue the next SET parameter.
a. Setting the Relative Mode reference value
Press the SET key to enter the Relative value setting mode. When in this mode, dashes
are displayed on the main display. Manually program the desired value via the numeric
keys. Press the ENTER key to store the relative value and move to the High / Low Limit
setting mode.
b. Setting the High and Low Alarm Limits
In the High Limit setting mode all dashes are initially displayed on the main display. Use
the numeric keys to program the desired High Limit value and then press ENTER to store
the value. Perform the same steps for setting the Low Limit value. The Elapsed Timer SET
mode is then queued.
c. Setting the Elapsed Timer
Use the numeric keys to enter the Hours, Minutes, and Seconds for the Timer. Press
ENTER to store this value and exit the SET mode.
T1/T2 T1-T2 (Second Display Input Selection)
This key doubles as the numeric ‘7’ key. Press this key to select which input is shown on
the secondary display (lower left display); T1 for thermocouple 1, T2 for thermocouple 2, or
T1-T2 to display the difference between the two thermocouples.
Type Key - Thermocouple Type for T2 input (Second Display)
This key doubles as the numeric ‘8’ key. Use the TYPE key to select the thermocouple
type (K, J, T, E, R, S, or N) for the T2 input. The input type is shown on the left side of the
LCD in smaller digits than for the T1 input. When the thermometer is turned on, it
remembers the type in use when the thermometer was last turned off.
Backlight Button
The backlight button (bottom right) doubles as the numeric ‘9’ key. Press the backlight
button to toggle the backlighting on and off. The backlight will switch-off automatically after
60 seconds to conserve battery life.
