Watlow Series 942 - Manual (Page 63)

WATLOW Series 942 User's Manual 63 Appendix
4-20mA Retransmit Field Calibration Procedure
Before attempting any calibration procedure, make sure you have the
proper equipment called for in each procedure.
Equipment Required
• 470
Ω
, 1/2 watt 10% resistor.
• 4 1/2 digit Digital Multimeter.
Setup and Calibration
1. Connect the AC line voltage L1, L2, and ground to the proper terminals of
the 942. See Chapter 2.
2. Connect the multimeter in series with the 470
Ω
resistor to Terminal #25
Positive and #24 Negative on the Series 945 terminal strip. Use regular
20 - 24 gauge wire.
3. Apply power to the unit and allow it to warm up for 15 minutes. After
warm-up put the unit in the CAL menu. See Page 54. Press the MODE
key until the O4LO parameter is displayed.
IMPORTANT:
When the RUN LED is ON the unit is automatically calibrating. Your
sequence is VERY important. Always move to the next parameter before
changing the calibration equipment. When you have completed all of the
4 - 20mA retransmit calibration parameters, press the HOLD/RUN key twice.
Failure to do so will result in inaccurate calibration values.
4. Press the HOLD/RUN key twice to enter the RUN mode. The unit is
calibrating when the RUN LED is ON. Make sure the unit is in the RUN
mode only when you are in the correct parameters. See Page 55.
5. At the O4LO parameter, the multimeter should read approximately 4mA.
Allow at least 10 seconds to stabilize.
6. Use the UP/DOWN keys (reverse acting) to adjust the reading on the
multimeter for 4.00mA. Press the MODE key.
7. At the O4HI parameter, the multimeter should read approximately 20mA.
Allow at least 10 seconds to stabilize. The unit will leave the CAL mode if 1
minute passes between key activations.
8. Use the UP/DOWN keys (reverse acting) to adjust the reading on the
multimeter for 20.00mA.
9. Press the HOLD/RUN key twice to exit the RUN mode. To conclude the
4 - 20mA retransmit calibration, advance the MODE key to the next param-
eter or exit the Calibration menu by pressing the HOLD/RUN key twice.
4-20mA Retransmit
NOTE
Before calibration
on an installed
control, make sure
all data and para-
meters are docu-
mented. See the
Setup and Operation
Tables, and the
Master Step Chart,
Pages 27, 30 and 35.