Set the signal type and the range of the instrument, then type any one of the signal, the percent, the real value or the PLC counts. The others fill in. Example: a 4-20 mA level transmitter on a 22 ft tank reads 12 mA at 50%, which is 11 ft.

1. The instrument range

Signal type Signal at 0% mA Signal at 100% mA Real value at 0% Real value at 100% Unit label (ft, psi, gpm, °F...) Relationship

2. Convert

Type in any box. The others update.

Signal mA Percent % Real value ft PLC counts

Counts scale Counts at 0% Counts at 100%

Points along the range

Percent	Signal	Value	Counts

The same point in every signal type

Useful for matching a 0-10 V input to a 4-20 mA output, or the other way around.

Signal type	At this point

Loop resistor (mA to volts)

A precision resistor turns a current loop into a voltage. 250 ohms turns 4-20 mA into 1-5 V.

Current mA Resistor Ω Voltage V

Loop power check

Does the supply have enough voltage at 20 mA?

Supply V Transmitter minimum V Receiver resistance Ω

Tank level to pressure

For a pressure transmitter at the bottom of an open tank. Use this to find the pressure range to set for the tank height.

Liquid height Height unit Specific gravity (water = 1)

0-10 V to 4-20 mA converter

Both signals are straight lines over the same percent of range. 0 V is 4 mA, 10 V is 20 mA, and 5 V is 12 mA. The table of every signal type shows the same point in 4-20 mA, 0-20 mA, 1-5 V and the others.

Steps

The signal type is set to 0-10 V. Type a voltage and read the percent.
Open the table of every signal type to see the matching mA value.
To go the other way, choose 4-20 mA and type the current.

Example

5 V on a 0-10 V signal is 50%, which is 12 mA on a 4-20 mA loop. 2.5 V is 25%, which is 8 mA.

Questions

What is the formula?: mA = 4 + 1.6 x volts for a 0-10 V signal to 4-20 mA.
Can I connect a 0-10 V output to a 4-20 mA input?: Not directly. They need a converter or isolator. This page only works out the matching values.

4-20 mA converter