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Calibration
Current loop (analog output) calibration
Calibrating the current loop adjusts the 4–20mA output to a reference—either the PLC/DCS
or a certified ammeter. It forces the 4mA and 20mA outputs to the external reference. The
current loop is pre-adjusted at the Ohmart factory with a certified ammeter, so it is usually
very close to the outputs required.
Analog output
Output signals are available through two channels. The two channels can control the output
that goes to the devices that use the analog output. Some of these devices are:
•
Controller
•
Indicator
•
Chart recorder
Each channel can be set up and calibrated to accommodate one of the following:
•
4–20mA
•
0–20mA
•
0–100mV
Analog output #1 ties to the product code at Item No. 10 and 11 of the Product Code Table.
The second analog output is not product dependent.
Select the output range for each channel from screen 63. If voltage is desired, the choice of
0–20 is made on screen 63 and requires hardware jumpering.
The objective of calibrating the analog output is to set the low signal (4mA, 0mA, or 0mV)
equal to the actual low process value (or lowest value of interest), and to equate the high
signal (20mA or 100mV) to the high process value (or highest value of interest). Refer to
Figure 24 for jumper information.
Calibration of the analog output signal
Calibrate the analog output signal by monitoring the current with a DC milliammeter.
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W-4510 Weigh Scale Technical Reference Manual
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