Hi everyone,
I've been running a Huawei SUN2000 with an EMMA-A02 and hit two frustrating problems that are well
known in this community:
- Modbus only allows one active client — HA and EVCC can't share the connection without stepping on
each other. - The EMMA restarts whenever it loses Huawei cloud connectivity, taking down HA sensors with it.
I solved both with a transparent Modbus TCP proxy running on an ESP32. It sits between the EMMA and
any number of clients (HA, EVCC, whatever), handles multiplexing, and maintains its own reconnection
logic independently of the cloud.
Features:
- Up to 4 simultaneous Modbus TCP clients
- Web dashboard showing connection status and client history
- Live transaction log with register-level detail
- Web-based config (WiFi / Ethernet, static or DHCP, EMMA IP/port)
- Headless WiFi setup mode on first boot
- OTA firmware updates
Screenshots:
(attach the three screenshots here)
Hardware: Any ESP32 with WiFi. I use it over Ethernet for stability but WiFi works fine too.
Repo: GitHub - mcamposv/modbusproxy: huawei modbus tcp proxy · GitHub
It's been working reliably in my setup. Happy to answer questions or take feedback — especially from
anyone running EMMA-A02 since support for that device is still a bit rough in the official
integration.