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DSMR Splitter

Active port expander for the P1 port on a Dutch Smart Meter (DSMR).

Introduction

This is an active port expander for DSMR 5.0. Contrary to simple splitting cables, this exapander buffers telegrams, and provides a dedicated port to connected devices.

Enclosed splitter. Enclosure removed facing front-side. Bottom side of the PCB.

Advantages

This design solves two (potential) issues compared to other splitters:

  • Some port splitters have a primary and a secondary port. Only the primary port has the data-request line connected to the DSMR. This means that the secondary port cannot request telegrams on its own and depends on the device connected to the master port.
  • A device connected to the secondary port could receive out-of-sync, if it depends on the data-request line. This could lead to incomplete/corrupt telegrams.

See this for more information.

Features

  • 3-port splitter.
  • DSMR 5.0.
  • No external power supply needed.

The splitter provides galvanic isolation between ports, if the 5 V is not used. To read more on how this was achieved, see this.

Furthemore, it requires a DSMR 5.0 meter because it provides 5 V power. Do note that the power (5 V, 250 mA) provided by the DSMR has to be shared among all readers, and the splitter itself requires ~50 mA.

Older DSMR versions can be supported by changing the firmware and providing 5 V externally.

Contents

  • The 3d/ folder contains a 3D-printable design for an enclosure.
  • The firmware/ folder contains the RIOT-OS firmware used for the microcontroller.
  • The pcb/ folder contains the Kicad schema and board design.
  • The tools/ folder contains additional tools, such as a DSMR simulator.

License

The work in this repository is covered by CC BY-NC-SA 4.0. See the LICENSE.md file for more information.