Raphael Ramos

I am trying to integrate Huawei ESM-48100U2 batteries with Home Assistant using ESPHome/Modbus RTU and would appreciate any technical insight regarding protocol details and register maps. What I have discovered/tested so far: Battery: - Huawei ESM-48100U2 - Possible slave ID: 214 - Communication settings: - 9600 baud - 8E1 (8 data bits, EVEN parity, 1 stop bit) Hardware used: - ESP32 - MAX485 - MAX490 - ESPHome Tests performed: ------------------------------------------------ 1) MAX485 RS485 2-wire - Partial communication achieved - Received: - CRC errors - truncated responses - UART echo At some moments I received valid Modbus exceptions: - 0x83 exception 2 - 0x84 exception 1 This indicates: - slave 214 is responding - protocol is likely Modbus RTU - but register/function selection may be wrong ------------------------------------------------ 2) MAX490 RS422 4-wire - Tried separating: - T+/T- - R+/R- Received strange/partial UART responses: - 94 0A 2F FF ... No stable valid Modbus frames. ------------------------------------------------ 3) Important discovery from forum Found this thread: https://powerforum.co.za/topic/16372-huawei-esm-48100b1-changing-slave-id/ Important information found: - Default slave ID = 214 - Communication = 9600 8E1 - Huawei implementation is described as “slightly outside standard Modbus” - Requires repeated polling attempts - Another user succeeded using FTDI RS485 adapter Most important finding: RJ45 pinout: - pins 1 and 4 = A - pins 2 and 3 = B This strongly suggests: - duplicated 2-wire RS485 - NOT classic RS422 full duplex ------------------------------------------------ 4) Registers found in forum Supposed register map: - 0x0000 = busbar voltage - 0x0001 = battery voltage - 0x0002 = current - 0x0003 = SOC - 0x000E = mode ------------------------------------------------ 5) Registers I already tested Tested: - 74 - 802 - 1000 - 1329 Results: - some returned Modbus exceptions - some returned partial responses - still no confirmed valid readings ------------------------------------------------ 6) Current ESPHome setup Using: - modbus_controller - slave 214 - 9600 EVEN - tested function 03 and 04 Examples: - function 03 -> exception 2 - function 04 -> exception 1 ------------------------------------------------ Next step: I will test using a USB RS485 adapter directly on PC with: - QModMaster - Modbus Poll Planned wiring: - Huawei pins 1 + 4 -> A - Huawei pins 2 + 3 -> B Questions: 1) Has anyone successfully integrated ESM-48100U2? 2) Is the register map above correct? 3) Is there any byte swap/endian requirement? 4) Is this really standard Modbus RTU? 5) Which function code should be used?