Small things — big energy savings

16 Apr 2023 at 22:00
Small things can make a big difference. Here is how the Anybus development team at HMS Networks in Sweden, has been able to take several measures to make their Anybus communication products save power.

Sometimes, small things can make a big difference. The Anybus NP40 network processor is a small chip – only 17x17 millimeters in size, but it handles communication for many of the world’s industrial machines and devices.

The Anybus development team at HMS Networks in Sweden, has been able to take several measures to make their Anybus communication products save power. And since Anybus products are shipped by the millions each year, the potential savings are substantial.

HMS Networks has an ambitious sustainability goal of becoming net positive when it comes to CO2 emissions by 2025. This means that all teams need to turn every stone to look for sustainability gains.

One team that has had this top of mind is the Anybus development department in Halmstad, Sweden. They develop world-leading Anybus industrial communication products which enable industrial machinery to communicate on any industrial network (hence the name Anybus).

Three small measures – big effects

Anybus NP40 is the high-performance network processor which handles the communication in popular Anybus products such as  Anybus CompactCom or  Anybus Communicator.

As with most industrial applications – Anybus products need to be “always on” and that is why energy-saving measures can have a big effect – especially if they are used in millions of applications.

Timmy Brolin, Principal Engineer at HMS’s Anybus development team describes three recently implemented initiatives.

You have implemented sleep mode for the CPU whenever there is no work to do. What are the effects of that?

“Even though we are using low-power embedded CPUs, they still consume a bit of power. We have been able to reduce the average power consumption by approximately 100mW (milliwatt) just by making sure the CPU core is put to sleep mode whenever there is no work to do.

This is sometimes as simple as adding just one or a few lines in the codebase. And while 100mW may not seem like much initially, it does add up to surprisingly large numbers when products are produced in the millions.”

(See calculation example at the end.)

You have also replaced built-in regulators with switching buck regulators, how does that work?

“Certain types of components, such as microcontrollers, communication controllers and Ethernet PHYs*, typically require one low voltage power supply for the core and a higher voltage supply for the I/Os**.
Some of these components come with a built-in linear power regulator for the core, so that it can run from a single higher voltage power supply such as 3.3V. However, these built-in linear regulators are not particularly efficient, so they waste power.

In a recent design, we disabled a built-in regulator which had an efficiency of 36%, and added a buck regulator*** from Texas Instruments with 90% efficiency. This change reduced the total power consumption by approximately 150mW.
Although the extra regulator increases the initial cost of the product slightly, it actually saves more money for the customer down the line as it reduces energy use.”

What energy-savings are possible with modern energy-efficient Ethernet PHYs?

"Some years ago, a revised version of the standard for 10Mbit Ethernet was introduced called 10BASE-Te. This revision fixes a legacy problem for Ethernet PHY designers, and allows an Ethernet PHY to be better optimized for 100Mbit and gigabit operation with lower voltages, without sacrificing compatibility with the old higher voltage 10Mbit version of Ethernet.

By replacing older Ethernet PHYs with modern ones designed in accordance with the 10BASE-Te revision, we have reduced the power consumption per Ethernet port by approximately 190mW when operating in 100Mbit mode.

This power saving has turned out to be the most significant, given that the majority of our products have two or more Ethernet ports each.” 

Samuel Alexandersson is Business Line Director at HMS’s Business Unit Anybus:

“Although we are talking energy-savings in milliwatts here, the big effect comes from the scale of things as the Anybus communication modules are so widely used. Last year, HMS shipped 1,2 million Anybus products. According to our calculations, the potential annual energy savings of these implementations are higher than what HMS as a company consumes over a year."

Samuel Alexandersson sees a large demand for energy saving measures going forward.

“Our industrial customers are doing all they can to save energy these days and with energy prices soaring, small things like these can really make a big difference in reducing the energy consumption and CO2 emissions of industrial machinery.”

* PHY refers to the physical layer in the OSI model – in this case the component which drives the electrical signal on the Ethernet cable.

**I/O – inputs and outputs

*** A buck regulator is a DC-to-DC power converter which steps down voltage (while stepping up current) from its input.


Milliwatts matter - A calculation exercise

Let’s say that an industrial product that is “always on” can reduce its energy consumption by 100 milliwatts (as the Anybus example above), the results can be:

0,1 watt
24 hour-use
365 days
20 year’s use
1,000,000 sold products
17,52 Gigawatt hours

(17,52 Gigawatts hours can power 18 million homes for an hour.)