Scrape serial port for text data and publish on MQTT

readserial.py

#!/usr/bin/python3
#
#simple app to read string from serial port
#and publish via MQTT
#
#uses the Python MQTT client from the Mosquitto project
#http://mosquitto.org
#
#Andy Piper http://andypiper.co.uk
#2011/09/15

import serial
import os
import binascii
import time 
import paho.mqtt.client as mqtt
import paho.mqtt.publish as publish


serialdev = '/dev/ttyUSB0'
broker = "127.0.0.1"
port = 1883


#MQTT callbacks

def on_connect(rc):
    if rc == 0:
    #rc 0 successful connect
        print("Connected")
    else:
        raise Exception


def on_publish(val):
    print("Published ", val)


#called on exit
#close serial, disconnect MQTT

def cleanup():
    print("Ending and cleaning up")
    ser.close()
    mqttc.disconnect()


try:
    print("Connecting... ", serialdev)
    #connect to serial port
    ser = serial.Serial(serialdev, baudrate=9600, timeout=20)
except:
    print("Failed to connect serial")
    #unable to continue with no serial input
    raise SystemExit


try:
    ser.flushInput()
    #create an mqtt client
    mypid = os.getpid()
    client_uniq = "power-pub-"+str(mypid)
    mqttc = mqtt.Client(client_id=client_uniq)

    #attach MQTT callbacks
    mqttc.on_connect = on_connect
    mqttc.on_publish = on_publish

    #connect to broker
    mqttc.connect(broker, port, 60)

    #remain connected to broker

    #marker byte-sequences:
    start = '1b1b1b1b01010101'
    end = '1b1b1b1b1a'

    data = ''
    reading = {}
    lastReading = None

    while True:
        bytes = ser.read(1)
        bytestring = binascii.hexlify(bytes).decode('ascii')
        data = data + bytestring
        #print(bytestring + ' ', end='', flush=True)

        pos = data.find(start)
        if (pos != -1):
            data = data[pos:len(data)]
        pos = data.find(end)
        if (pos != -1):
            #print('found ' + data[16:pos] + '\n')

            search = '070100020800ff'
            pos = data.find(search)
            if (pos != -1):
                pos = pos + len(search) + 20
                value = data[pos:pos + 10]
                scale = pow(10,-1) # todo: read from data
                energyWatth = int(value, 16) * scale
                energyKWh = energyWatth / 1000.0 
                #print('Power Sent     (' + search + ') : 0x', value, ' = ', "{:10.3f}".format(energyKWh), ' kWh')
                publish.single("net-power/sent-total", payload=energyWatth, qos=0, retain=False)
                reading['sent-total'] = energyWatth

            search = '070100010800ff'
            pos = data.find(search)
            if (pos != -1):
                pos = pos + len(search) + 20
                value = data[pos:pos + 10]
                scale = pow(10,-1) # todo: read from data
                energyWatth = int(value, 16) * scale
                energyKWh = energyWatth / 1000.0 
                #print('Power Received (' + search + ') : 0x', value, ' = ', "{:10.3f}".format(energyKWh), ' kWh')
                publish.single('net-power/recieved-total', payload=energyWatth, qos=0, retain=False)
                reading['received-total'] = energyWatth


            search = '070100010700ff'
            pos = data.find(search)
            if (pos != -1):
                pos = pos + len(search) + 14
                value = data[pos:pos + 8]
                power = int(value, 16) / 1e2
                print ('W: ' + search + ' = ' + value + ' = ' + str(power) + ' W')

            readingTime = time.time()
            reading['time'] = readingTime

            if (lastReading is not None):
                lastReadingTime = lastReading['time']
                duration = readingTime-lastReadingTime
                if (duration > 10.0):
                    consumptionWh = (reading['received-total'] - lastReading['received-total']) - \
                                    (reading['sent-total'] - lastReading['sent-total'])
                    consumptionWs = consumptionWh * 3600.0;
                    timestamp = time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(readingTime))

                    print(timestamp, 'Average Power Consumption, 10s:', '{:0.1f}'.format(consumptionWs/duration), 'Watt')

                    # Reset reading:
                    lastReading = reading.copy() 
                    reading = {}
                #else:
                    #print('Elapsed', "{:2.1f}".format(duration)+ 's. ', 'Collecting...')
                    #print('lastReading ', str(lastReading))
                    #print('reading     ', str(reading))
            else:
              print('initializing lastRead.')
              lastReading = reading.copy() # initial setting

            data = ''

#        print("got ", line)
        #split line as it contains V,temp
        #list = line.split(",")
        #second list element is temp
        #temp = 1
        #list[1].rstrip()
        #mqttc.publish("net-power/rec", temp)
        #pass


# handle list index error (i.e. assume no data received)
except (IndexError):
    print("No data received within serial timeout period")
    cleanup()
# handle app closure
except (KeyboardInterrupt):
    print("Interrupt received")
    cleanup()
except (RuntimeError):
    print("uh-oh! time to die")
    cleanup()

readserial.py.old

#!/usr/bin/python3
#
#simple app to read string from serial port
#and publish via MQTT
#
#uses the Python MQTT client from the Mosquitto project
#http://mosquitto.org
#
#Andy Piper http://andypiper.co.uk
#2011/09/15

import serial
import os
import paho.mqtt.client as mqtt

serialdev = '/dev/ttyUSB0'
broker = "127.0.0.1"
port = 1883


#MQTT callbacks

def on_connect(rc):
    if rc == 0:
    #rc 0 successful connect
        print("Connected")
    else:
        raise Exception


def on_publish(val):
    print("Published ", val)


#called on exit
#close serial, disconnect MQTT

def cleanup():
    print("Ending and cleaning up")
    ser.close()
    mqttc.disconnect()


try:
    print("Connecting... ", serialdev)
    #connect to serial port
    ser = serial.Serial(serialdev, baudrate=9600, bytesize=7, parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, timeout=20)
except:
    print("Failed to connect serial")
    #unable to continue with no serial input
    raise SystemExit


try:
    ser.flushInput()
    #create an mqtt client
    mypid = os.getpid()
    client_uniq = "arduino_pub_"+str(mypid)
    mqttc = mqtt.Client(client_id=client_uniq)

    #attach MQTT callbacks
    mqttc.on_connect = on_connect
    mqttc.on_publish = on_publish

    #connect to broker
    mqttc.connect(broker, port, 60)

    #remain connected to broker
    #read data from serial and publish
    while mqttc.loop() == 0:
        line = ser.readline()
        print("got ", line)
        #split line as it contains V,temp
        #list = line.split(",")
        #second list element is temp
        temp = 1
        #list[1].rstrip()
        mqttc.publish("net-power/rec", temp)
        pass


# handle list index error (i.e. assume no data received)
except (IndexError):
    print("No data received within serial timeout period")
    cleanup()
# handle app closure
except (KeyboardInterrupt):
    print("Interrupt received")
    cleanup()
except (RuntimeError):
    print("uh-oh! time to die")
    cleanup()