P
AGE
51
be displayed for ten seconds, then SCAn for ten seconds. The instrument will compute and
display the cold junction temperature to the nearest tenth of a degree C. Compare reading
with thermometer and use the UP and DOWN keys to correct the reading, if necessary. To
end the procedure press the SCROLL key and CAL3 will be displayed again.
The instrument may stay in SCAn. To establish a reasonable starting point, with SCAn
displayed, press the SCROLL key. CAL3 should be displayed. With CAL3 displayed, while
pressing the DOWN key, press the SCROLL key. The instrument will display hoLd. Press
the UP key. The instrument will begin the calibration procedure with a default value and
proceed to deLy. Complete calibration as described above.
Error Recovery - see 5.4 ( page 56) for details on specific errors. The calibration can be
exited at any time. hoLd is displayed by pressing the SCROLL key.
5.2.4 CAL 4 COLD JUNCTION TEMPERATURE UTILITY
This procedure displays the temperature sensed by the cold junction compensator (CJC).
No special test equipment is required.
With CAL4 displayed, press and hold the DOWN key then press the SCROLL key and
release both keys. SCAn will be displayed for ten seconds while the instrument
computes the CJC temperature. The result will then be displayed to a tenth of a degree C.
The input terminals must be shorted with a jumper wire. Remember, the temperature
displayed is that of the CJC terminals not the ambient temperature. To exit, press the
SCROLL key and CAL4 will be displayed.
5.2.5 CAL 5 RTD INPUT
This procedure determines and saves calibration values which correct for component varia-
tions relating to RTD inputs. This calibration must be preceded by CAL2 to properly calibrate
the unit.
Test equipment needed will include a Decade Box (Resistance Substitution ) with .01%
resolution or equivalent. Make sure the jumpers JU1 (Processor Board), JU2 and JU3
(Options boards) are in the proper positions for RTD input. See Appendix A-2 (page 65) and
A-3 (page 66 and 67).
With CAL5 displayed press and hold the DOWN key, then press the SCROLL key and
release both keys. hLd1 will then be displayed. Connect the Decade Box at 100 ohm setting
across the input terminals 1 and 3 and Jumper terminals 1 and 5. Press the DOWN key and
dELy will be displayed for up to ten seconds, then SCAn for ten seconds. When hLd2 is
displayed, connect 277 ohms to the input and press the DOWN key. Again dELy will display
for up to ten 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 about specific errors.
The Calibration mode can be exited any time the unit displays hLd1 or hLd2 by pressing the
SCROLL key.
5.2.6 CAL 6 COLD JUNCTION ON/OFF
With CAL 6 displayed, while pressing the DOWN ARROW key, press the SCROLL key. The
instrument will display C6 and the number of the mode in effect. Mode 0 is the normal
operating mode. The cold junction compensation is on. Mode 1 is the cold junction compen-
sation disabled (off). Pressing the UP ARROW or DOWN ARROW will change the mode
selection. The Mode 1 functions to facilitate input testing with a non-temperature compen-
sated millivolt source used to simulate thermocouple input.
