How to convert a 4-20mA to 0-10V signal in an Arduino PLC
9 January, 2019 by
Boot & Work Corp. S.L., Support Team
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## What is a 4-20mA Signal

### Why is 4-20mA standard?

AÂ 4-20mA signalÂ is an Analog signal that, if connected to an Arduino board or an industrial Arduino-based PLC controller, identifies the value from the sensor. The controller receives a current from the sensor, allowing the Arduino PLC to transform that electrical signal to an understandable value, ready for being used on the software code. This value is used for the programmer to know the right units of measure received from that sensor and understand the Industrial project's situation.

4-20mA is mainly used for long-distanceÂ cables because the current signal receives less interference from noise or EMC issues than a voltage signal such as 0-10Vdc analog inputs.Â

Arduino is not able to receive a current analog signal because the analog signals fromÂ Arduino work from 0 to 5Vdc,Â so it is necessary to convert the current analog signal to a Voltage. It is important to know that Industry voltage analog signal standards work from 0 to 10Vdc, so the way to transform a 4-20mA to Arduino is quite different as transformed forÂ Arduino-based PLC, which works at 0-10Vdc.

## Converter circuit diagram for 4-20mA Analog Sensor to 0-10Vdc

It is necessary to convert aÂ 4-20mA to a 0-10Vdc signal. As you can see in the below diagram, you can understand how to transform a 4-20mA to 0-10v using Ohm Law.Â

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To do this, it is necessary to connect anÂ Â between the analog 4-20mA signal and the ground signal as shown in the diagram. If you do, the analog value will change from current to Voltage.

## How can you make a 4-20mA to 0-10V signal conversion on your industrial controller Arduino for industrial automation?

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Arduino as a single board is not able to be used in Industrial environments. For this reason, Industrial Shields has developed an Industrial Shield for Arduino which includes an original Arduino board inside, and it is fully compatible with Industrial Standards.

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It is easy to understand how to transform a 4-20mA to 0-10Vdc through a 500Ohm resistance through the Ohm Law. If you need to test it using an Arduino Uno, Arduino Mega, or Arduino Leonardo Boards, you must replace the 500 Ohms to 250 Ohms to transform 4-20mA to 0-5Vdc.

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If you want to test it easily you can use the Arduino IDE using the example â€śAnalog Inputâ€ť which allows the user to read the 10 bits Analog inputs from the Arduino to
0 â€“ 1023 values.
If you have not used Arduino IDE before, you can alsoÂ

## Requirements

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• Industrial Shields boards. To learn how to install the boards,Â .

### How does the input value change to Arduino?

When you have a signal of 4-20mA for 10 bits, you get the following data:

 4-20mA signal 10 bits 4mA 0 value 20mA 1023 value

But, if you convert this signal to 0-10Vdc, the results are:

 4-20mA 0-10Vdc 10 bits 4mA 2Vdc 204 value* (approximately) 20mA 10Vdc 1023 value

As you can see, the result of 4mA (2Vdc), is close to 204. Below is the linear graph where the results come from:

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Boot & Work Corp. S.L., Support Team
9 January, 2019