Analog signal types: 0-10V versus 4-20mA

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The two most common analog signal types in modern industrial automation are 4-20mA and 0-10V. Let’s take a look at the difference between the two and which one you should choose.


A 0-10V (or in some cases, 0-5V) analog signal uses voltage to represent a variable signal. It’s a simple method of analog signal transmission most commonly used in HVAC applications, but has some inherent disadvantages, including:

  • A sensor fault (no signal) cannot be detected: A value of 0V can indicate either zero value or no signal. It’s possible to work around this by using a 2-10V instead, but this is uncommon.
  • It is prone to electrical noise and interference.
  • Over longer cable distances, voltage drop can cause an inaccurate signal.
  • A separate power supply to the instrument is usually required, meaning the sensor requires at least three wires.


The 4-20mA current signal is becoming much more common for analog signal transmission in a lot of applications. A current signal offers some real world advantages, such as:

  • A no signal fault can easily be detected: 0mA indicates no signal, while 4mA indicates a zero value.
  • An instrument can be ‘loop-powered (often 24VDC) – mean it can be powered by the same cable that it transmits on, meaning only two wires are required.
  • It is much less prone to electrical noise, interference and voltage drop.

In addition, for many applications there is now a much wider range of 4-20mA instruments available than 0-10V. We recommend 0-10V should only be used where the automation equipment used is incapable of handling a 4-20mA signal.