23
While in the High or Low calibration pop-up screen use
the up and down arrows to change the output value
being read with the volt meter. Adjust the High value
for the 20 mA reading and the Low value for the 4 mA
value.
3.4
4-20mA Input Calibration
4-20mA inputs can be calibrated to insure that the input seen by the controller from the external device
match. It also allows for setting the 4-20mA input into a number range that relates to the value being read.
Select the Input to be calibrated
The
20mA
and
4mA
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raw analog to digital value is adjusted to match a 20mA
(full scale) and 4mA (bottom of scale) signal from
the external device inputting the 4-20mA input. The
external device must be connected to the controller
and showing either full scale or bottom of scale when
calibrating each. The number shown along with either
the 20mA or 4mA while calibrating is the raw A/D value
and is only a reference. A 20mA input should be around
5500 and 4mA around 1100. If the A/D numbers are
not in this range check input device.
The
MAX
and
LOW
calibration inputs are for telling the controller what to display for a 20mA input and a 4mA
input. For example if the input is a drum level sensor monitoring a 55 gallon drum the value for MAX should
be 55 and LOW should be 0. The controller then displays a number automatically ranging between 55 and
0 based on the input value. The units of measure (gallons for example) is set in the Customize menu from
the Home page.
OFFSET
- Changes the current displayed value of the 4-20mA input reading to allow for a manual 1pt
calibration of the displayed value.
FACTORY DEFAULT
- If the 20mA or 4mA calibration has been incorrectly set (not at 4 or 20) this will reset
the settings back to a factory value for 4 and 20.
