June 23, 2025
868 MHz or 433 MHz? The right choice for your wM-Bus
What exactly does “frequency band” mean in the context of wM-Bus? To transmit data wirelessly from meters, such as water meters, heat meters or RTN units. The digital signal must be modulated onto a carrier frequency. In Europe, this is typically done using ISM bands (Industrial, Scientific and Medical), most commonly 868 MHz and 433 MHz.
Wireless M-Bus (wM-Bus), a standard protocol for energy metering, operates within these frequency bands and uses different communication modes:
- T1 and C1 modes at 868.95 MHz
- S1 mode at 868.3 MHz
- T1 mode also exists for the 433 MHz band at 434.475 MHz
- There is also a 169 MHz band, which offers superior penetration through obstacles, but is used in niche applications only.
And what about proprietary protocols?
Not all meters comply strictly with T1/C1/S1 modes. Some manufacturers implement proprietary versions of wM-Bus tailored to their devices. However, these still usually operate within the 868 MHz or 433 MHz bands, since licensing other frequencies would be costly and complex. So how do you choose? ACRIOS converters support both frequency bands. The right version depends mainly on:
- Distance between converter and meter
- Physical obstacles in the environment
- Frequency band used by the meter (which is fixed at the factory and cannot be changed)
Why choose a converter for the 868 MHz band?
- This is the standard band for wM-Bus communication across the EU
- Compatible with T1/C1/S1 modes and OMS-compliant meters
- Ideal for typical residential, commercial or mixed-use installations
- May detect nearby 433 MHz signals, but only at short range
Why choose a converter for the 433 MHz band?
- Better signal penetration in difficult environments – shafts, basements, metal walls
- Suitable for urban areas with signal interference or heritage buildings
- Requires meters manufactured specifically for 433 MHz (non-switchable)
- Sometimes detects 868 MHz signals better than vice versa
What if your meters are available in both versions? In that case, focus on environmental factors. General recommendation:
- 868 MHz → go-to choice for standard installations
- 433 MHz → for hard-to-reach locations or heavy signal attenuation
Summary: frequency band selection by environment
FAQs
Does the EED directive define which frequency band to use?
Not directly. The EED mandates remote meter reading, but does not specify frequency bands or technical parameters.
What is the difference between 868 MHz and 433 MHz for wM‑Bus, and when does each make sense?
The EED does not define the frequency band. 868 MHz is the standard for wM‑Bus and offers broad compatibility; 433 MHz provides better penetration in harsh environments but may be subject to national limits on power or duty cycle.
Can the frequency band of a meter be changed after installation?
No. The frequency is defined at the manufacturing stage and cannot be changed later.
When does frequency 433 MHz make sense?
Whenever meters are installed in harsh environments (shafts, cellars, metal structures), and are available in 433 MHz versions.
Is the 433 MHz band legal across the EU?
Yes, it is part of the ISM band, though some countries impose restrictions on transmission power or duty cycle.
Not sure which converter version is right for you? Reach out to us and we’ll help you choose the ideal frequency band and hardware setup based on your meters and environment.
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