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--- projects:farmrobot:batteriemanagement [2021/03/21 18:23]
jonas
+++ projects:farmrobot:batteriemanagement [2021/03/21 19:02] (current)
jonas [Modbus Python and Watson-IoT MQTT publish on Raspberry Pi 4B]
@@ Line 104: / Line 104: @@
 ===== Modbus Python and Watson-IoT MQTT publish on Raspberry Pi 4B =====
-Using FTDI USB adapter which can be interfaced on /dev/ttyUSB0
+Using FTDI USB adapter which can be interfaced on /dev/ttyUSB0\\
+Adding the current user to the "dialout" user group to access serial interfaces without root permissions:
     sudo adduser pi dialout
+Installing prerequisites:\\
     sudo apt install python3
     wget https://bootstrap.pypa.io/get-pip.py
     sudo python3 get-pip.py
-    sudo pip install pymodbus
+    sudo pip install pymodbus\\
-\\
+ModbusSerialClient is the Modbus client that is used to interface the registers on the BMS:
     from pymodbus.client.sync import ModbusSerialClient
-Using IBM Watson IoT platform
+=== IBM Watson IoT platform ===
 Creating a new device and gathering credentials: https://q74k3e.internetofthings.ibmcloud.com/dashboard/devices/browse/
@@ Line 129: / Line 131: @@
     pip install wiotp-sdk
-Modbus communication implementation based on: https://github.com/clarkni5/tinybms/blob/master/python/tinybms.py
+Modbus communication implementation based on: https://github.com/clarkni5/tinybms/blob/master/python/tinybms.py\\
+=== Code: ===
 <file py pc_bms_modbus_mqtt.py>
 import numpy as np
 import wiotp.sdk.device
+from time import sleep
+from datetime import datetime
 import pymodbus.client.sync
-# Modbus client
 dev_port = '/dev/ttyUSB0'
-modbus_client = pymodbus.client.sync.ModbusSerialClient(method='rtu', port=dev_port, timeout=2, baudrate=115200)
+modbus_client = pymodbus.client.sync.ModbusSerialClient(method='rtu', port=dev_port, baudrate=115200, parity='N',
-modbus_client.connect()
+                                                        bytesize=8, stopbits=1, timeout=2, strict=False)
+my_config = wiotp.sdk.device.parseConfigFile("device.yaml")
+mqtt_client = wiotp.sdk.device.DeviceClient(config=my_config, logHandlers=None)
-myConfig = wiotp.sdk.device.parseConfigFile("device.yaml")
-mqtt_client = wiotp.sdk.device.DeviceClient(config=myConfig, logHandlers=None)
+def connect_modbus():
-mqtt_client.connect()
+    if not modbus_client.is_socket_open():
+        modbus_client.connect()
+    print("connect_modbus: ok")
+def connect_mqtt():
+    mqtt_client.connect()
+    print("connect_mqtt: ok")
@@ Line 151: / Line 164: @@
 def read_registers(address, count):
-    return modbus_client.read_holding_registers(address, count, unit=0xAA).registers
+    while True:
+        result = modbus_client.read_holding_registers(address, count, unit=0xAA)
+        if not result.isError():
+            register = result.registers
+            return register
-modbus_client.read_holding_registers(0, 1, unit=0xAA)
+def ask_registers():
+    read_registers(0, 1)
+    lifetime_counter = (convert(read_registers(32, 2), np.uint32))/60  # min
+    time_left = (convert(read_registers(34, 2), np.uint32))/60  # min
+    pack_voltage = convert(read_registers(36, 2), np.float32)  # V
+    pack_current = convert(read_registers(38, 2), np.float32)  # C
+    min_cell = (read_registers(40, 1)[0])/1000  # V
+    max_cell = (read_registers(41, 1)[0])/1000  # V
+    cell_diff = (read_registers(104, 1)[0])/10000  # V
+    soc = (convert(read_registers(46, 2), np.uint32))/1000000  # %
+    bms_temperature = (read_registers(48, 1)[0])/10  # °C
+    bms_online = hex(read_registers(50, 1)[0])
+    max_discharge_current = (read_registers(102, 1)[0])/1000  # A
+    max_charge_current = (read_registers(103, 1)[0])/1000  # A
+    charge_count = read_registers(111, 1)[0]
-lifetime_counter = convert(read_registers(32, 2), np.uint32)
+    f_data = {
-time_left = convert(read_registers(34, 2), np.uint32)
+        'lifetime_counter': "%.2f" % lifetime_counter,
-pack_voltage = convert(read_registers(36, 2), np.float32)
+        'time_left': "%.2f" % time_left,
-pack_current = convert(read_registers(38, 2), np.float32)
+        'pack_voltage': "%.2f" % pack_voltage,
-min_cell = read_registers(40, 1)[0]
+        'pack_current': "%.2f" % pack_current,
-max_cell = read_registers(41, 1)[0]
+        'min_cell': "%.2f" % min_cell,
-cell_diff = read_registers(104, 1)[0]
+        'max_cell': "%.2f" % max_cell,
-soc = convert(read_registers(46, 2), np.uint32)
+        'cell_diff': "%.2f" % cell_diff,
-bms_temperature = read_registers(48, 1)[0]
+        'soc': "%.2f" % soc,
-bms_online = read_registers(50, 1)[0]
+        'bms_temperature': "%.1f" % bms_temperature,
-max_discharge_current = read_registers(102, 1)[0]
+        'bms_online': str(bms_online),
-max_charge_current = read_registers(103, 1)[0]
+        'max_discharge_current': "%.2f" % max_discharge_current,
-charge_count = read_registers(111, 1)[0]
+        'max_charge_current': "%.2f" % max_charge_current,
+        'charge_count': str(charge_count)
+        }
+    print(f_data)
+    print("stored register values: ok")
+    return f_data
-myData = {
-    'lifetime_counter': lifetime_counter,
+def publish(p_data):
-    'time_left': time_left,
+    mqtt_client.publishEvent(eventId="status", msgFormat="json", data=p_data, qos=0, onPublish=print("publish: ok"))
-    'pack_voltage': pack_voltage,
-    'pack_current': pack_current,
-    'min_cell': min_cell,
+def output_time():
-    'max_cell': max_cell,
+    now = datetime.now()
-    'cell_diff': cell_diff,
+    current_time = now.strftime("%H:%M:%S")
-    'soc': soc,
+    print("-------------------------------------------------------------------")
-    'bms_temperature': bms_temperature,
+    print(current_time)
-    'bms_online': bms_online,
+    print("-------------------------------------------------------------------")
-    'max_discharge_current': max_discharge_current,
-    'max_charge_current': max_charge_current,
-    'charge_count': charge_count
+while True:
-    }
+    output_time()
-mqtt_client.publishEvent(eventId="status", msgFormat="json", data=myData, qos=0, onPublish=None)
+    connect_modbus()
-mqtt_client.disconnect()
+    connect_mqtt()
+    my_data = ask_registers()
+    publish(my_data)
+    sleep(10)
 </file>
+{{:projects:farmrobot:run_terminal.png|}}
+==== Receiving MQTT messages on Watson IoT platform ====
+Received messages:\\
+{{:projects:farmrobot:watson_iot_received_messages.png?600|}}\\
+Raw status data available:\\
+{{:projects:farmrobot:watson_iot_raw_data.png?600|}}
+===== Web Interface to view and graph the data =====
+An easy way to set up a web interface is to host a node-red instance on a server, for example on a stationary Raspberry Pi 4, which can be accesses via network or can be made accessible with port forwarding from the internet.\\
+Setting up a Raspberry Pi 4B with docker and docker run portainer.
+Create a new Node-Red Stack with a compose file, which creates a node-red web instance on the device on port 1880.
+The ip adress is needed which can be requested with:
+    ifconfig
+<file yaml compose.yaml>
+version: "2"
+services:
+  node-red:
+    image: nodered/node-red:latest
+    environment:
+      - TZ=Europe/Berlin
+    ports:
+      - "1880:1880"
+    networks:
+      - node-red-net
+    volumes:
+      - ~/data/node-red:/data
+networks:
+  node-red-net:
+</file>
+The node-red webapp can then be accessed via [[http://ip-adress:1880]]\\
+The Node-RED Dashboard module is needed to display the data with node-red\\
+To install, click the Menu Button and choose "Manage palette". Click the "Install" tab and search for "node-red-dashboard".\\
+Then click on install and install in the pop-up window. Then return to the main view.\\
+{{:projects:farmrobot:node-red-palette.png?600|}}
 ===== Micropython implementation on espressiv ESP32 DevKitc v4 =====
 Required software: Linux OS and python3 (sudo apt-get install python3)

FabLab Kamp-Lintfort

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