Contents
User Guide
This measurement to current converter tool will convert any linear measurement reading into the ideal current loop signal over a linear range of 4 to 20 milliamps, and display a 4-20mA conversion scale for the chosen measurement range.
Formula
This tool uses the following formula to calculate the current output signal over a 4-20mA scale from a specified measurement input reading and range:
Linear mA out = 4 + (16 x ((Rdg – Low Limit) / (High Limit – Low Limit)))
Parameters
Measurement Unit
Add the measurement parameter value in the specified measurement unit you wish to convert.
Measurement Reading
Add the measurement parameter value you wish to convert in any units.
Lowest Measurement
Enter the lower limit for the measurement range to be converted. For example zero would be a typical value for most instrumentation but you can also add negative (-) or positive (+) values as well. Please enter the value in the same units as specified for all other input values.
Highest Measurement
Enter the upper limit for the measurement range to be converted, e.g. full scale or full range. This value can be negative (-) or positive (+). Please enter the value in the same units as specified for all other input values.
Current Loop Signal (4-20mA) – Answer
This is the ideal converted signal for the input measurement range specified, and represents the ideal output reading excluding all measurement and instrumentation errors. The calculated result is displayed in milliamps (mA) based on a linear 4 to 20 mA scaling.
Help
Calculator precision
How precise is the calculation from measurement to linear 4-20mA output?
The linear 4 to 20 milliamp signal Answer is displayed to a precision of 9 significant figures.
Measurement types
What type of measurement can I convert?
Any measurement which is linearly proportional to the 4-20mA signal can be converted, such as pressure, temperature, force, load, weight, position, movement, speed, rpm, depth, level, etc…
Input & Output
Does it matter if the measurement is an input or a output?
No it does not matter if the measurement, the calculation is the same whether it is an input or an output.
Bidirectional measurements
Can I convert a bidirectional measurement?
Yes, you can enter the lowest measurement as a negative value by prefixing it with a minus (-) sign.
Compound ranges
Can I enter a compound range?
Yes, any negative range can be specified in the Lowest text box can be combine with any positive range specified in the Highest text box.
Elevated zero point
Is it possible to convert a measurement range where the lowest value is offset in positive direction from zero?
Yes, the lowest measurement point can start from any value above zero.
Measurement accuracy checking
Can this converter help to determine the accuracy of measurement instrument?
Yes, this converter will calculate the ideal 4-20mA signal so that you can compare it to an observed 4-20mA reading.
0-30,000 psi conversion
What are the 4-20mA readings for a 0-30,000 psi range?
This conversion scale shows the pressure values against discreet milliamp values:
0 bar over -1 to 3.5 bar conversion
If a transmitter range is -1 to 3.5 bar, then what will be the mA reading at 0 bar?
At 0 bar it will be 7.5 mA for a linear 4-20mA output signal.
