4-20mA Absolute Encoders


The 4-20mA analog output absolute encoder is one of easiest to understand.

Many absolute encoders provide their position information via a communications fieldbus protocol, such as Ethernet I/P, CanOpen, EtherCAT, Profibus etc, to the control or display system.

In order to test, check, or fault find such a fieldbus system you need special programming tools and access to the programming environment. This usually entails a laptop, some special software, cables, and some training.

The advantage of a 4-20mA  analog signal from the encoder, means that anyone with a multi-meter can quickly check the status of the encoder signal information.

Another advantage of a 4-20mA signal is that it is relatively noise (electrical) immune, and is suitable to run over longer distances, even a few hundred meters.

Communications protocols sometimes attract a royalty charge from the developers making them more expensive; whereas a 4-20mA signal is as royalty free as the sunshine.

The one down side is that an analog input on a PLC is not cheap, and you need as many analog channels as device signals on the project. Whereas a single communications port can accept inputs from multiple encoders.

POSITAL FRABA offer a wide range of encoders with a 4-20mA output. The more cost effective and common single turn encoder is by default 0 ~ 360° = 4-20mA, and since these are programmable encoders, PCA can easily reconfigure these locally to any angle range in between.

4-20mA encoder programming chart

Multiturn encoders are also available for up to 16 revolutions or 5760°  

Aside from the 4-20mA analog standard, POSITAL also offer encoders with a 0-10V signal, or even 0-5V signal output option.

Another feature with POSITAL’s 4-20mA analog encoders, is that the direction the signal travels in can be reversed by simply applying the supply voltage to one of the pins. Similarly there is a zero° pin, which allows you to set the home position, or top-dead-centre (TDC) position, so that it becomes the 4mA position.

For contact PCA for further information on our range of 4-20mA absolute encoders. A member of our expert team will gladly answer any questions that you may have. 


If so, why not share it with your peers and colleagues. Simply click on the blue LinkedIn share icon below.

15 October 2021