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5.2.4 CAL4 COLD JUNCTION UTILITY
This procedure displays the temperature the cold junction compensator is sensing. No test
equipment is required.
With CAL4 displayed, press and hold the DOWN key, then press the SCROLL key. Release
both keys and SCAn will be displayed for 10 seconds while the instrument senses the CJC
temperature. The result will then be displayed to a tenth of a degree C. The input terminals
must be shorted. CAL3 must first be performed.
The displayed temperature is not the
ambient temperature. It is the temperature of the CJC. To exit, press the SCROLL key
and CAL4 will be displayed.
5.2.5 CAL5 RTD INPUT
This procedure determines and saves calibration values relating to RTD inputs. This
calibration must be preceded by CAL2 to properly calibrate the instrument. A decade
resistance substitution box with .01% resolution or equivalent is required.
Make sure that the
Processor board jumper JU1 is in the non-volt position (Appendix A-2, page 64) and
that the Option board jumpers JU2 and JU3 are in the proper positions (Appendix A-3,
page 65).
With CAL5 displayed, press and hold the DOWN key and then press the SCROLL key. The
display will now be hLd1 to indicate that the instrument is set to calibrate the RTD input.
Connect the decade box at 100 ohm setting across the input terminals 1 and 3 and a jumper
wire from terminal 1 to 5. Press the DOWN key and dELy will be displayed for 10 seconds,
then SCAn for ten seconds. When hLd2 is displayed, change the decade box setting to 277
ohms to the input terminals (do not disturb the wiring) and press the DOWN key. The display
will change to dELy for 10 seconds, followed by SCAn for ten more seconds. CAL5 will be
displayed after the calibration is completed.
Error recovery:
See section 5.4 (page 56) for details on specific errors.
The calibration can be exited when the instrument displays hLd1 or hLd2 by pressing the
SCROLL key.
5.2.6 CAL6 COLD JUNCTION COMPENSATION
This routine provides selection of operating modes for the cold junction compensation used
for thermocouple inputs.
With CAL6 displayed, press and hold the DOWN key, then press the SCROLL key. The
instrument will display C6 and the number of the mode in effect. Press the UP or DOWN key
to change the mode selection, indicated by the number to the right of the C6. Pressing the
SCROLL key will exit the calibration with the last number displayed in effect.
The selected mode will remain in effect if power is interrupted. To return the instrument to
normal operation, CAL6 must be exited, with mode zero selected, or CAL1 must be executed
to initalize all parameters.
Mode 0: Normal operating mode.
Mode 1: Cold Junction Compensation temperature will be internally fixed at 0 degrees C by
the software to facilitate linearization testing when using an uncompensated millivolt source to
simulate thermocouple millivolt input signal.
Note: If the Process Value exceeds 999.9, the leftmost digit will be the letter o with a bar over
it. The other digits will be valid.