Rasperry Pi, Python, SDS011, Thingspeak channel update, Help appreciated.

Hello Community,

first of all let me admit, that I am - according to python - a "script-kiddie". I recently learned html5, css3 and javascript, but that is not helpful here. That is why I need your help.

I found a script that is reading the data from my sds011 sensor. It passes its data to a webpage. So far so good. Now I would like to pass the data to thingspeak. After a couple of hours trying without really understanding I would appreciate help. I think the code line below ist the one I need for updating my channel in thingspeak. But the channel remains empty. No data shown. What have I done wrong? Help appreciated. Learning python is on my "To-Do-List" ;-)

Kind regards,

Roger

Short code:

import urllib

....

urllib.request.urlopen("https://api.thingspeak.com/update?api_key=RJASGFLWRVM5JKHM&field1=pm25&field2=pm10")

The entire code:

#!/usr/bin/python -u

# coding=utf-8

# "DATASHEET": http://cl.ly/ekot

# https://gist.github.com/kadamski/92653913a53baf9dd1a8

from __future__ import print_function

import serial, struct, sys, time, json, subprocess

import urllib

DEBUG = 0

CMD_MODE = 2

CMD_QUERY_DATA = 4

CMD_DEVICE_ID = 5

CMD_SLEEP = 6

CMD_FIRMWARE = 7

CMD_WORKING_PERIOD = 8

MODE_ACTIVE = 0

MODE_QUERY = 1

PERIOD_CONTINUOUS = 0

JSON_FILE = '/var/www/html/aqi.json'

MQTT_HOST = ''

MQTT_TOPIC = '/weather/particulatematter'

ser = serial.Serial()

ser.port = "/dev/ttyUSB0"

ser.baudrate = 9600

ser.open()

ser.flushInput()

byte, data = 0, ""

def dump(d, prefix=''):

print(prefix + ' '.join(x.encode('hex') for x in d))

def construct_command(cmd, data=[]):

assert len(data) <= 12

data += [0,]*(12-len(data))

checksum = (sum(data)+cmd-2)%256

ret = "\xaa\xb4" + chr(cmd)

ret += ''.join(chr(x) for x in data)

ret += "\xff\xff" + chr(checksum) + "\xab"

if DEBUG:

dump(ret, '> ')

return ret

def process_data(d):

r = struct.unpack('<HHxxBB', d[2:])

pm25 = r[0]/10.0

pm10 = r[1]/10.0

checksum = sum(ord(v) for v in d[2:8])%256

return [pm25, pm10]

#print("PM 2.5: {} μg/m^3 PM 10: {} μg/m^3 CRC={}".format(pm25, pm10, "OK" if (checksum==r[2] and r[3]==0xab) else "NOK"))

def process_version(d):

r = struct.unpack('<BBBHBB', d[3:])

checksum = sum(ord(v) for v in d[2:8])%256

print("Y: {}, M: {}, D: {}, ID: {}, CRC={}".format(r[0], r[1], r[2], hex(r[3]), "OK" if (checksum==r[4] and r[5]==0xab) else "NOK"))

def read_response():

byte = 0

while byte != "\xaa":

byte = ser.read(size=1)

d = ser.read(size=9)

if DEBUG:

dump(d, '< ')

return byte + d

def cmd_set_mode(mode=MODE_QUERY):

ser.write(construct_command(CMD_MODE, [0x1, mode]))

read_response()

def cmd_query_data():

ser.write(construct_command(CMD_QUERY_DATA))

d = read_response()

values = []

if d[1] == "\xc0":

values = process_data(d)

return values

def cmd_set_sleep(sleep):

mode = 0 if sleep else 1

ser.write(construct_command(CMD_SLEEP, [0x1, mode]))

read_response()

def cmd_set_working_period(period):

ser.write(construct_command(CMD_WORKING_PERIOD, [0x1, period]))

read_response()

def cmd_firmware_ver():

ser.write(construct_command(CMD_FIRMWARE))

d = read_response()

process_version(d)

def cmd_set_id(id):

id_h = (id>>8) % 256

id_l = id % 256

ser.write(construct_command(CMD_DEVICE_ID, [0]*10+[id_l, id_h]))

read_response()

def pub_mqtt(jsonrow):

cmd = ['mosquitto_pub', '-h', MQTT_HOST, '-t', MQTT_TOPIC, '-s']

print('Publishing using:', cmd)

with subprocess.Popen(cmd, shell=False, bufsize=0, stdin=subprocess.PIPE).stdin as f:

json.dump(jsonrow, f)

if __name__ == "__main__":

cmd_set_sleep(0)

cmd_firmware_ver()

cmd_set_working_period(PERIOD_CONTINUOUS)

cmd_set_mode(MODE_QUERY);

while True:

cmd_set_sleep(0)

for t in range(15):

values = cmd_query_data();

if values is not None and len(values) == 2:

print("PM2.5: ", values[0], ", PM10: ", values[1])

time.sleep(2)

# open stored data

try:

with open(JSON_FILE) as json_data:

data = json.load(json_data)

except IOError as e:

data = []

# check if length is more than 100 and delete first element

if len(data) > 100:

data.pop(0)

# append new values

jsonrow = {'pm25': values[0], 'pm10': values[1], 'time': time.strftime("%d.%m.%Y %H:%M:%S")}

data.append(jsonrow)

# save it

with open(JSON_FILE, 'w') as outfile:

json.dump(data, outfile)

if MQTT_HOST != '':

pub_mqtt(jsonrow)

#!!!!!!!!!!!!!!!!!!! HERE

urllib.request.urlopen("https://api.thingspeak.com/update?api_key=RJASGFLWRVM5JKHM&field1=pm25&field2=pm10")

print("Going to sleep for 2 min...")

# Alter time.sleep = 1200

cmd_set_sleep(1)

time.sleep(120)

[Roger Notknomuch]

In the meantime I found a solution.

For anybody who is interested. I added a writing method using websockets...

Here is the entire script:

#!/usr/bin/python -u

# coding=utf-8

# "DATASHEET": http://cl.ly/ekot

# https://gist.github.com/kadamski/92653913a53baf9dd1a8

from __future__ import print_function

import serial, struct, sys, time, json, subprocess

####### ADDED

import paho.mqtt.publish as publish

import psutil

import string

# The ThingSpeak Channel ID.

# Replace <YOUR-CHANNEL-ID> with your channel ID.

channelID = "1061352"

# The write API key for the channel.

# Replace <YOUR-CHANNEL-WRITEAPIKEY> with your write API key.

writeAPIKey = "RJASGFLWRVM5JKHM"

# The hostname of the ThingSpeak MQTT broker.

mqttHost = "mqtt.thingspeak.com"

# You can use any username.

mqttUsername = "Roger NotKnoMuch"

# Your MQTT API key from Account > My Profile.

mqttAPIKey = "GIE04M6OE1XPQWX0"

# Define websocket on Port 80

tTransport = "websockets"

tPort = 80

# Create the topic string.

topic = "channels/" + channelID + "/publish/" + writeAPIKey

######## ADDED END

DEBUG = 0

CMD_MODE = 2

CMD_QUERY_DATA = 4

CMD_DEVICE_ID = 5

CMD_SLEEP = 6

CMD_FIRMWARE = 7

CMD_WORKING_PERIOD = 8

MODE_ACTIVE = 0

MODE_QUERY = 1

PERIOD_CONTINUOUS = 0

JSON_FILE = '/var/www/html/aqi.json'

MQTT_HOST = ''

MQTT_TOPIC = '/weather/particulatematter'

ser = serial.Serial()

ser.port = "/dev/ttyUSB0"

ser.baudrate = 9600

ser.open()

ser.flushInput()

byte, data = 0, ""

def dump(d, prefix=''):

print(prefix + ' '.join(x.encode('hex') for x in d))

def construct_command(cmd, data=[]):

assert len(data) <= 12

data += [0,]*(12-len(data))

checksum = (sum(data)+cmd-2)%256

ret = "\xaa\xb4" + chr(cmd)

ret += ''.join(chr(x) for x in data)

ret += "\xff\xff" + chr(checksum) + "\xab"

if DEBUG:

dump(ret, '> ')

return ret

def process_data(d):

r = struct.unpack('<HHxxBB', d[2:])

pm25 = r[0]/10.0

pm10 = r[1]/10.0

checksum = sum(ord(v) for v in d[2:8])%256

return [pm25, pm10]

#print("PM 2.5: {} μg/m^3 PM 10: {} μg/m^3 CRC={}".format(pm25, pm10, "OK" if (checksum==r[2] and r[3]==0xab) else "NOK"))

def process_version(d):

r = struct.unpack('<BBBHBB', d[3:])

checksum = sum(ord(v) for v in d[2:8])%256

print("Y: {}, M: {}, D: {}, ID: {}, CRC={}".format(r[0], r[1], r[2], hex(r[3]), "OK" if (checksum==r[4] and r[5]==0xab) else "NOK"))

def read_response():

byte = 0

while byte != "\xaa":

byte = ser.read(size=1)

d = ser.read(size=9)

if DEBUG:

dump(d, '< ')

return byte + d

def cmd_set_mode(mode=MODE_QUERY):

ser.write(construct_command(CMD_MODE, [0x1, mode]))

read_response()

def cmd_query_data():

ser.write(construct_command(CMD_QUERY_DATA))

d = read_response()

values = []

if d[1] == "\xc0":

values = process_data(d)

return values

def cmd_set_sleep(sleep):

mode = 0 if sleep else 1

ser.write(construct_command(CMD_SLEEP, [0x1, mode]))

read_response()

def cmd_set_working_period(period):

ser.write(construct_command(CMD_WORKING_PERIOD, [0x1, period]))

read_response()

def cmd_firmware_ver():

ser.write(construct_command(CMD_FIRMWARE))

d = read_response()

process_version(d)

def cmd_set_id(id):

id_h = (id>>8) % 256

id_l = id % 256

ser.write(construct_command(CMD_DEVICE_ID, [0]*10+[id_l, id_h]))

read_response()

def pub_mqtt(jsonrow):

cmd = ['mosquitto_pub', '-h', MQTT_HOST, '-t', MQTT_TOPIC, '-s']

print('Publishing using:', cmd)

with subprocess.Popen(cmd, shell=False, bufsize=0, stdin=subprocess.PIPE).stdin as f:

json.dump(jsonrow, f)

if __name__ == "__main__":

cmd_set_sleep(0)

cmd_firmware_ver()

cmd_set_working_period(PERIOD_CONTINUOUS)

cmd_set_mode(MODE_QUERY);

while True:

cmd_set_sleep(0)

for t in range(15):

values = cmd_query_data();

if values is not None and len(values) == 2:

print("PM2.5: ", values[0], ", PM10: ", values[1])

time.sleep(2)

# open stored data

try:

with open(JSON_FILE) as json_data:

data = json.load(json_data)

except IOError as e:

data = []

# check if length is more than 100 and delete first element

if len(data) > 100:

data.pop(0)

# append new values

jsonrow = {'pm25': values[0], 'pm10': values[1], 'time': time.strftime("%d.%m.%Y %H:%M:%S")}

data.append(jsonrow)

# save it

with open(JSON_FILE, 'w') as outfile:

json.dump(data, outfile)

if MQTT_HOST != '':

pub_mqtt(jsonrow)

###### ADDED

# get the system performance data over 20 seconds.

pm25 = values[0]

pm10 = values[1]

# build the payload string.

payload = "field1=" + str(pm25) + "&field2=" + str(pm10)

# attempt to publish this data to the topic.

try:

publish.single(topic, payload, hostname=mqttHost, transport=tTransport, port=tPort,auth={'username':mqttUsername,'password':mqttAPIKey})

print (" Published Data = ",pm25," and ", pm10," to host: " , mqttHost , " clientID= " , clientID)

except (KeyboardInterrupt):

break

except:

print ("There was an error while publishing the data.")

###### ADDED END

print("Going to sleep for 1 min...")

# Alter time.sleep = 1200

cmd_set_sleep(1)

time.sleep(1200)

Answer 1

[Roger Notknomuch]

Problem solved