EPEVER solar charger - ModBus via RP2040 CircuitPython

Written in CircuitPython for a Raspberry RP2040 PICO W board. The software run asynchronously an read all configured registers out from the EPEVER device. Via MQTT data can be send to a MQTT-Broker (in my case ioBroker with installed MQTT extension)

Please NOTE: Exception handling is poor implemented. Will work on this issue next time. Currently there is a bug in blinking the error LED. If PICO is connected via USB and startet via Thonny, every thing works well. If running stand alone after few ModBus requests the LED blinks 6x (indicator for MQTT Problem) but there is no problem, data is transfered correctly.

History

Version	Date	Info
0.1.0	2023-01-05	initial version working with EPEVER XTRA 4415n
0.2.0	2023-01-07	MQTT implementation, some bugfixes. First stable release
0.2.1	2023-01-08	Bugfixings

Release Notes

0.2.1

• Fixing a mqtt-publishing error, that occurs on topic _LAST_RUN_. Transfer now a json.dumps(payload)
• Fixing an error on data which represent a binary information (like register 3200, 3201). The value is not converted into a 16bit binary string
• Printing IP-Address into log

0.2.0

First running version incl. MQTT

Quick Overview

The software is devided into several parts and classes

• SolarPICO: Main modul. From here all other parts are called
• ModBusRTU: Base class for ModBus devices
• EPEPVER: Define all function codes and register for reading, decoding and converting data
• SolarMQTT: Simple class to send data to a MQTT-Broker
• settings.toml Configuration file
• folder lib includes all necessary adafruit libraries
• folder doc some interesting additional documents
• folder img images for this README
• folder backup can be ignored

Dependencies

• You need a PICO with WLAN

• CircuitPython 8.0.x installed on your RP204 device. Software was not tested with 7.3.3 or below

• Connection cable to your EPEVER device. Use an standard RJ45 Ethernet cable and cut one plug to connec to the RS485 adapter

• Adapter to convert RS485 to UART => Amazon-Link

• Install Thonny-IDE for easy working with your PICO. Follow installation instructions

Installation

• install CircuitPython on your device. Please follow instruction form CircuitPython.org.
• Test your RP2040. Is it connected to your computer? Can you access to the device with your file explorer?
• download this github repo to your local computer into a folder
• copy this files onto your PICO

(the backup-folder is not part of the repo ! Ignore it ;-)

Wiring

Configuration

Open in Thonny the file settings.toml

General settings

Normally you should nothing change in this section

################################################
# GENERAL
################################################
UART0_TX = "GP0"
UART0_RX = "GP1"
UART1_TX = "GP4"
UART1_RX = "GP5"

WLAN

Configure your SSID and password for access to your WLAN. After configuration, please restart your PICO and check if this device can be pinged

################################################
# WiFI-Configuration
################################################
CIRCUITPY_WIFI_SSID="<ssid>"
CIRCUITPY_WIFI_PASSWORD="<password>"

EPEVER

• EPEVER_UART. Please configure 0 (UART0) or 1 (UART1)
• EPEVER_LOGLEVEL explicit EPEVER logging level.
• EPEVER_INTERVAL how often should the registered read (in milliseconds). Avoid to fast reading (< 500
• EPEVER_TOPIC_KEY="register": possible values: identifier or register
  If identifier is used, sub-topic name is value from the identifier-key from register dict (e.g. A1-A10 or Bx-By ...)
  if register is used, sub-topic name is the register-address (e.t "3100", "32xy", ...)

################################################
# EPEVER
################################################
EPEVER_DEMO="True"
EPEVER_INTERVAL = 5000
EPEVER_VERSION = "V 0.1.0"
EPEVER_UART=1
# 10=Debug, 20=Info, 30=Warning, 40=Error, 50=Critical
EPEVER_LOGLEVEL=20
EPEVER_TOPIC_KEY="identifier"

MQTT

• MQTT_BROKER_IP : insert the IP-Adress from your MQTT-Broker
• MQTT_PORT : default port is 1883
• MQTT_PREFIX : root folder in the topic payload.
• MQTT_TOPIC : topic name (e.g. DeviceName)
• MQTT_USER : MQTT-User
• MQTT_PW : MQTT-Users password
• MQTT_LOGLEVEL : explicit MQTT Logging level

################################################
# MQTT-Configuration
################################################
MQTT_BROKER_IP="<mqtt-broker ip address>"
MQTT_PORT=1883
MQTT_PREFIX="RP2040_SOLAR"
MQTT_TOPIC="EPEVER"
MQTT_USER="<user>"
MQTT_PW="<password>"
# 10=Debug, 20=Info, 30=Warning, 40=Error, 50=Critical
MQTT_LOGLEVEL=20

HeardBeat

This section is used to indicate, that the system is running or if an error occured with a blinking led

• HEARTBEAT_INTERVAL how often a heart beat signal should raised (default 5000ms)
• HEARTBEAT_IDLE_INTERVAL used as blinking frequence (do not change)
• HEARTBEAT_ERROR_INTERVAL if an error occured, this is the blinking frequence (default 500ms, 2x sec)
• HEARTBEAT_IDLE if no error occured, PICO blinks 1x per HEARTBEAT_INTERVAL with HEARTBEAT_IDLE_INTERVALms
• HEARTBEAT_ERROR_MODBUS blinks 3x times if something goes wrong with your modbus device
• HEARTBEAT_ERROR_MQTT blinks 6x if something goes wrong with MQTT
• HEARTBEAT_ERROR_WLAN blinks 5x if something goes wrong with your WLAN connection

################################################
# HEART-BEAT
################################################
HEARTBEAT_INTERVAL = 5000
HEARTBEAT_IDLE_INTERVAL = 150
HEARTBEAT_ERROR_INTERVAL = 500
HEARTBEAT_IDLE = 1
HEARTBEAT_ERROR_BMS = 2
HEARTBEAT_ERROR_MODBUS = 3
HEARTBEAT_ERROR_INVERTER = 4
HEARTBEAT_ERROR_WLAN = 5
HEARTBEAT_ERROR_MQTT = 6

Running your system

if everything is installed properly on your PICO start inside Thonny the file SolarPico.py After this log entries should be visible in the terminal window.

V 0.1.0

 _____  _____  _____  _____  _____  _____ 
|   __||  _  ||   __||  |  ||   __|| __  |
|   __||   __||   __||  |  ||   __||    -|
|_____||__|   |_____| \___/ |_____||__|__|                                                                                                                               
    
V 0.1.0
>>>>>>>>> FCode '03'
---------- Register '9000'
5249.771: INFO - SEND:		bytearray(b'010390000001a90a')	(8)
5251.838: INFO - RECEIVE:
raw:		0103020000b844
decoded:	{'03': ['0x1', '0x3', '0x2', '0x0']}
converted:	{'len': 2, 'info': '', 'value': 0.0, 'type': 'E1', 'register': '9000', 'unit': 'Type', 'fcode': '03'}
>>>> HEART-BEAT <<<< 0.15/1

Troubleshooting

Python exceptions occured

Please check which kind of exception occured. Maybe your lib folder was not copied successfully or you use an inproper circuitpython version

No response from EPEVER

Your PICO send periodically a sequence like 5249.771: INFO - SEND: bytearray(b'010390000001a90a') (8) to your EPEVER. If the hardware connection is correct installed your EPEVER answer with an payload like this

raw:		0103020000b844
decoded:	{'03': ['0x1', '0x3', '0x2', '0x0']}
converted:	{'len': 2, 'info': '', 'value': 0.0, 'type': 'E1', 'register': '9000', 'unit': 'Type', 'fcode': '03'}

If you do not get a receive message please check your hardware configuration. In most times there is something wrong with your setup

• which UART do you use on your PICO? 0 or 1? Please double check if you connected to the correct pins on your board
• TX PICO must be connected to TX on your adapter board
• RX PICO must be connected to RX on your adapter board
• GND on your adapter board must be connected to RJ45 Pin 8 or 7
• PORT A on your adapter board must be connected to RJ45 Pin 6 or 5
• PORT B on your adapter board must be connected to RJ45 Pin 4 or 3

DeepDive for developers

SolarPICO.py

Central script to call periodically the EPEPER device and send the result via MQTT to your Broker

Class Interval

Only used for storing an interval value for running tasks

Class ErrObj

Only used to store an error code. This code indicates the error with a blinking led on your PICO

Class EPEVER

Configure all possible (usefull) EPEVER function codes and register to read. Collected data are represented as

• raw bytearray 0103020069786a
• decoded as a dict {'03': ['0x1', '0x3', '0x2', '0x69']}
• converted as dict for human reading : {'len': 2, 'info': '', 'value': 1.05, 'type': 'E2', 'register': '9001', 'unit': "'Ah", 'fcode': '03'}

Class ModBusRTU

Currently this ModBus class can only READ from a ModBus device. No WRITING back to the device is implemented

Class SolarMQTT

Base MQTT-Client class. This can be used for any MQTT-Client connections to your own broker

Class IOBrokerMQTT

Derived class from SolarMQTT to facilitate the conversion of EPEVER data into MQTT topics.