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)

4-20 mA to PSI converter

A pressure transmitter spreads its range across 4 to 20 mA. On a 0 to 100 psi transmitter, 4 mA is 0 psi and 20 mA is 100 psi. Change the range to match your device.

Steps

The range is set to 0-100 psi. Change the real values at 0% and 100% to match your transmitter.
Type the mA reading to see psi, or type psi to see the mA.
Use the counts box if you need the value your PLC card reports.

Example

On a 0-100 psi transmitter, 12 mA is 50 psi, 8 mA is 25 psi, and 16 mA is 75 psi.

Questions

How do I find psi from mA?: psi = (mA - 4) / 16 x range. On a 0-100 psi device at 10 mA, that is 6 / 16 x 100 = 37.5 psi.
Is that gauge or absolute?: It follows the transmitter. A gauge transmitter reads gauge pressure and an absolute one reads absolute.

4-20 mA converter