Temperature Control
Oven status
In isothermal operation ( 
RATE 
= 0 ), if 
INIT TIME 
is set equal to 0 (zero), the HP 5890 internally sets run time to the maximum, 650 minutes.
A 
is included in key sequences defining parameters for a second ramp; B 
is included in key sequences defining parameters for a third ramp.
In isothermal operation, and in one•or two•ramptemperature programs, rate for the next ramp must be set to 0 (zero) to prevent further programming.
In oven temperature programming, once any one of the five temperature
programming functions ( INIT TEMP | , | INIT TIME , RATE , FINAL TEMP , and |
FINAL TIME ) is displayed, pressing | ENTER | , without entering a new |
setpoint value, rolls the display successively through the entire group, (including A and B displays for second and third ramps).
This is an efficient way in which to review and, if necessary, change oven temperature program setpoints.
Oven status
During a temperature•programmedrun, the LED OVEN display provides indication of oven status at any given time:
CIsothermal Run: Assuming 
INIT TIME 
is assigned a value greater than 0, and that 
RATE 
= 0, only the INITIAL TIME LED is lit. It remains lit throughout the run.
CSingle•Ramp Temperature Program: The three LEDs, INITIAL TIME, RATE, and FINAL TIME, successively light to indicate position in the temperature program.
CMultiple•Ramp Temperature Program: The three LEDs, INITIAL TIME, RATE, and FINAL TIME, successively light to indicate position in the first temperature program ramp.
Then RATE and FINAL TIME LEDs light alternately as the program proceeds through the second (and third) ramp(s).
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