P
AGE
46
Error Recovery - see 5.4 (page 52) for details. However, be sure that the millivolt source is
securely connected, functioning properly and the polarity is correct. Press the DOWN key to
bring the instrument back to dELy and try the calibration again. The calibration can be exited
at anytime hLd1 or the reference number is displayed by pressing the SCROLL key.
CAL 2 QUICK CALIBRATION
This routine wil allow the operator to execute a rough calibration on their unit via the keypad
with no other equipment or disturbance to established wiring. It is intended to provide a partial
recovery from a calibration corruption where the necessary equipment indicated in Cal 2-5
may not be available. It should be noted that this is not intended as a substitution to the main
calibration procedure described earlier and may considerably deter from the accuracy of the
instrument.
With CAL2 displayed, press and hold the DOWN ARROW key, then press the SCROLL key.
Release both keys and the instrument will display hLd1. Press and hold the UP ARROW key,
then press the SCROLL key. The display will momentarily blank and then CAL1 will be
displayed. Release both keys and depress the UP ARROW key. CAL will be displayed.
5.2.3 CAL 3 COLD JUNCTION COMPENSATION
This procedure determines and saves calibration values which correct component variations
relating to the cold junction compensation. This calibration must be preceeded by CAL2, the
main calibration, to properly calibrate the instrument. These two calibrations are the only
ones needed for proper operation with a thermocouple input.
Test equipment: one type J thermocouple and one mercury thermometer, accurate to
±
.25
degrees C or equivalent are required.
Make sure all input wiring is disconnected and connect the J thermocouple to the input. Place
the thermometer next to the thermocouple and allow the controller to warm up for 30 minutes,
before proceeding with the calibration.
With CAL3 displayed, depress and hold the DOWN key. Then press the SCROLL key and
the unit will display hoLd. Release both keys. Press the DOWN key and deLy will be
displayed for ten seconds, then SCAn for ten seconds. If SCAn remains in the display for
much longer than ten seconds, refer to the note below. 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.
NOTE: If the instrument continues to display in SCAn, proceed as follows. With SCAn
displayed, press the SCROLL key. CAL3 should be displayed. With CAL3 displayed, while
pressing the DOWN key, press and release 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 52) 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.
