Operating the Analyzer
Operator’s Manual 2
–41
Scaling and Calibrating the Current Loop Signal
The 4-20 mA current loop signals are most conveniently scaled and calibrated
at the receiving end (RTU, flow computer, etc.).
To scale the receiver’s output, the analyzer’s current loop output is forced to
4 mA (0%) and 20 mA (100%) using the 4-20 mA Test parameter. The
receiver is adjusted to read “0” and “Full Scale,” respectively.
Toscalethecurrentloopsignal
1. Make sure the current loop is connected and the receiver is set for
the analyzer to source the current.
2. Set the 4-20 mA Test parameter to 0% (see “To change
parameters in Mode 2” on page 2-15).
3. Enter Mode 5 by pressing the # key followed by the 5 key to force
the loop current to 4 mA.
4. Adjust the receiver calibration control to read the appropriate value.
A current loop output of 4 mA represents the value set in AO 4 mA
Value.
5. Set the 4-20 mA Test parameter to 100%.
6. Enter Mode 5 by pressing the # key followed by the 5 key to force
the loop current to 20 mA.
7. Adjust the receiver calibration controls for the appropriate value. A
current loop output of 20 mA represents the value set in AO 20 mA
Value.
8. If needed, repeat steps 2-7 to obtain an accurate calibration over the
range.
9. After obtaining an accurate calibration of the current loop receiver,
press the # key followed by the 1 key to return to Normal Mode.
The 4-20 mA current loop output is factory set to source current.
To change the 4-20 mA current loop output from source to sink,
refer to the section called “Changing the 4-20 mA Current
Loop Mode” in the Hardware Manual.
Be sure to work in a non-hazardous area while handling any
electrical connector.
When the # key is pressed, measurement will be suspended until
a new mode is established. The only modes that produce
measurements are Mode 1, Mode 6, Mode 7 or Mode 8.
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