4 rtd current calibration, 5 calibration recall – Monarch Instrument DC 2000 User Manual
Page 121
Chapter 6 Calibration
Page 6-3
Figure 6-1
Calibration
Resistor
Connection
6.4 RTD Current Calibration
The ADC current source is used for RTD measurements and needs calibration for the RTD’s.
6.4.1 Calibrating the RTD Current
The following procedure contains step-by-step instructions on calibrating the current source. A 250
Ω
±0.05%
resistor must be connected across the + and - terminals of a free input and the current source return path C
must be connected to the - input terminal. The Recorder then applies 1mA of current through the resistance to
calibrate current. These programming steps are discussed in menu order.
NOTE: Before calibrating currents, ensure that the zero calibration and 1.25 Volt Scale range has been
calibrated per the above, as this will affect the accuracy of Current Calibration.
6.4.1.1 Connecting Resistance
Select a free set of input terminals on the rear of the unit, or remove any connections
from the set of terminals to be used. Connect the 250
Ω
±0.05% resistor across the +
and - terminals of this input and connect the current source return path C to the - input
terminal (see Figure 6-1).
6.4.1.2 Calibrating the RTD Current
The following steps are used to guide the user in calibrating current.
In the Hidden Menu, use the UP (
↑
) or DOWN (
↓
) Arrow Keys to select “ADC control”
and press ENTER. Use the UP (
↑
) or DOWN (
↓
) Arrow Keys to select “Cal ADC” and
press ENTER. Use the UP (
↑
) or DOWN (
↓
) Arrow Keys to select “Cal Currents” and
press ENTER. Use the UP (
↑
) or DOWN (
↓
) Arrow Keys to select the Input Number to
which the resistor is connected, 1, 2, 3, 4, 5 or 6 and press ENTER. To allow the
Recorder to detect the actual value of the current, press ENTER. The Recorder program
will store the adjusted value from a nominal 1mA of current. Calibration of Currents is
complete.
6.5 Calibration Recall
If the calibration equipment listed above is not available, the factory calibration for the zero calibration and scales
(sections 6.2 and 6.3) can be recalled. All channels will be recalled.
In the Hidden Menu, use the UP (
↑
) or DOWN (
↓
) Arrow Keys to select “ADC control” and press ENTER. Use the
UP (
↑
) or DOWN (
↓
) Arrow Keys to select “Cal ADC” and press ENTER. Use the UP (
↑
) or DOWN (
↓
) Arrow Keys
to select “Cal Recall” and press ENTER. At the prompt “Are You Sure?” press YES to retrieve the factory calibration
settings or press NO to exit without changing the calibration settings.