Press the "SET" button to accept the new scan rate and continue.
S
7.5
Set-point Resistance
To display the Set-point Resistance, press the "SET" and "DOWN" buttons si-
multaneously when the temperature is displayed. When the "SET" and
"DOWN" buttons are released the temperature is again displayed. This value
is used to calibrate the unit and is not adjustable.
7.6
Temperature Scale Units
To toggle between °C and °F, press the "SET" and "UP" keys simultaneously
when the temperature is displayed.
7.7
Secondary Menu
Functions used less often are accessed within the secondary menu. Press
and hold the "SET" and EXIT buttons to access the secondary menu. The
first function in the secondary menu is the heater power display. (See Figure
4 on page 20.)
7.8
Heater Power
The temperature controller controls the temperature of the well by pulsing
the heater on and off. The total power being applied to the heater is deter-
mined by the duty cycle or the ratio of heater on time to the pulse cycle
time. By knowing the amount of heating the user can tell if the instrument
is heating "UP" to the set-point, cooling "DOWN", or controlling at a constant
temperature. Monitoring the percent heater power lets the user know the
stability of the well temperature. With good control stability the percent
heating power should not fluctuate more than ±1% within one minute.
The heater power display is accessed in the secondary menu. Press and
hold the "SET" and "EXIT: buttons. The heater power is displayed as a per-
centage of full power.
100.0 C
S+E
SEC
Accept scan rate
Target temperature
Access heater power in percent
Flashes
heater power
for secondary menu and then displays the
7
Controller Operation
23