Smart Energy Meter with AWS cloud

Stage 1 : Testing ModDus Communication (RS485) using modpoll
Step 1: Connect the A & B of energy meter to A & B pin in RuggedBoard RS485 port respectively.
For demonstration purpose I have used Elmeasure LG+ 1119 meter. If you are having any other meter then you have to read the datasheet of the meter vendor and provide proper parameters. 
Step 2: Download the modpoll ARM execulatble binary and save it into your work directory. To download the file click below.
modpoll.bin
644KB
Binary
modpoll.bin
Step 3: Save the following code in .sh format on your working directory and name is as mbpoll.sh
1
./modpoll.bin -m rtu -a 1 -t 4:float -r 159 -b 9600 -s 1 -p none /dev/ttyS2
Copied!
The above script has the following components:
m : communication mode
a : Slave address
t : data types of the slave holding register
r : Start Reference
b : Baudrate
s : Stopbits
p : Parity Bit
SERIALPORT : Serial port node of the RS485
Step 4: Run the above code to test ModBus communication
sh mbpoll.sh
If everything is correct your code will run without any error. and you can proceed to next stage.
Stage 2: Reading the Energy Meter values using Python 3 Script.
Step 1: Connect the energy meter and the board as shown in the Stage 1.
Step 2: write the following code and save it as read_energymeter.py
1
#Python code to read data from Energy Meter:
2
​
3
from pymodbus.client.sync import ModbusSerialClient as ModbusClient
4
from pymodbus.payload import BinaryPayloadDecoder
5
from pymodbus.payload import BinaryPayloadBuilder
6
from pymodbus.constants import Endian
7
import time
8
​
9
client = ModbusClient(method='rtu', port='/dev/ttyS2', stopbits=1, bytesize=8, baudrate=9600, parity='N')
10
​
11
connection = client.connect()
12
​
13
counter = 1
14
​
15
while True:
16
​
17
    print("==========================================================")
18
    print("Iteration {}" .format(counter))
19
    print("----------------------------------------------------------")
20
​
21
    WattHour = client.read_holding_registers(0x009E, 2, unit=1)
22
    decoder = BinaryPayloadDecoder.fromRegisters(WattHour.registers, Endian.Big, wordorder=Endian.Little)
23
​
24
    print("Watt Hour Reading:", float(decoder.decode_32bit_float()))
25
​
26
    counter += 1
27
​
28
    print("==========================================================")
29
​
30
    time.sleep(2)
31
​
32
​
Copied!
Step 3: Run the above code to read data from Energy Meter
python read_energymeter.py
If everything is correct your code will run without any error and you can proceed to next stage to send the data to a AWS cloud and view it on a dashboard.
Stage 3: Reading the Energy meter values using Python 3 Script 
I this stage you will be able to send command from cloud server (AWS) and start replying to the request from cloud. In this example we will send a command from cloud to start sending Energy Meter data and stop sending when the timer is out.
Step 1: Connect the energy meter and the board as shown in the Stage 1.
Step 2: Write the following code and save it as lg1119.py
1
#-------------------AWS MQTT init----------------------
2
import paho.mqtt.client as paho
3
import ssl, random
4
from time import sleep
5
import os
6
import json
7
import threading
8
​
9
#-----------------MODBUS init---------------------------
10
from pymodbus.client.sync import ModbusSerialClient as ModbusClient                                                     
11
from pymodbus.payload import BinaryPayloadDecoder                                                                       
12
from pymodbus.payload import BinaryPayloadBuilder                                                                   
13
from pymodbus.constants import Endian                                                                                   
14
                                                                                                                    
15
​
16
#----------------Modbus client connection-------------------                                                                                                                        
17
modclient = ModbusClient(method='rtu', port='/dev/ttymxc5', stopbits=1, bytesize=8, baudrate=9600, parity='N')               
18
connection = modclient.connect() 
19
​
20
​
21
#----------------Global Variables----------------------------
22
Message = ''
23
TIMER = 0
24
Wflag = 0
25
​
26
mqtt_url = "a3hf64x6hul7tx-ats.iot.us-west-2.amazonaws.com"
27
root_ca = '/home/root/certs/Amazon_Root_CA_1.pem'
28
public_crt = '/home/root/certs/c17983007e-certificate.pem.crt'
29
private_key = '/home/root/certs/c17983007e-private.pem.key'
30
​
31
​
32
#----------------Functions-----------------------------------
33
def ledOn():
34
  os.system("echo 29 > /sys/class/gpio/export")
35
  os.system("echo out > /sys/class/gpio/PA29/direction")
36
  os.system("echo 1 > /sys/class/gpio/PA29/value")
37
  os.system("echo 29 > /sys/class/gpio/unexport")
38
​
39
​
40
def ledOff():
41
  os.system("echo 29 > /sys/class/gpio/export")
42
  os.system("echo out > /sys/class/gpio/PA29/direction")
43
  os.system("echo 0 > /sys/class/gpio/PA29/value")
44
  os.system("echo 29 > /sys/class/gpio/unexport")
45
​
46
def publishOn():
47
  client.publish("Aws_regor", '{"voltage":' + str(Volt_val) + ', "frequency":' + str(Freq_val) + ', "status": "ON", "kwh":' + str(kWh_val) + ', "cost":' + str(cost) + '}', qos = 1)
48
​
49
def publishOff():
50
  client.publish('Aws_regor', '{"voltage":' + str(Volt_val) + ', "frequency":' + str(Freq_val) + ', "status": "OFF", "kwh":' + str(kWh_val) + ', "cost":' + str(cost) + '}', qos = 1)
51
 
52
​
53
def timerCb():
54
  global Message
55
  global TIMER
56
  global Wflag
57
  print("Timer elapsed\n\nTurning off")
58
  #ledOff()
59
  publishOff()
60
  #client.publish('Aws_regor', '{"voltage":' +str(Volt_val)', "frequency":' +str(Freq_val)', "message": "OFF"}', qos = 1)
61
  Message = ''
62
  TIMER = 0
63
  Wflag = 0
64
  
65
​
66
def on_connect(client, userdata, flags, rc):
67
  print("Connected with result code " + str(rc))
68
  client.subscribe("ExampleTopic")
69
  print("Subscribed")
70
​
71
​
72
def on_message(client, userdata, msg):
73
  global Message
74
  global TIMER
75
  global timer
76
  global Wflag
77
  print ("Message Received")
78
  print (msg.payload.decode("utf-8"))
79
  msg.payload=msg.payload.decode("utf-8")
80
  recvMesg = msg.payload
81
  jsonMesg = json.loads(recvMesg)
82
  Message = jsonMesg['message']
83
  if (Message == 'ON'):                             
84
    TIMER = jsonMesg['timer']
85
    timer = threading.Timer(TIMER * 60, timerCb)
86
    #ledOn()
87
    timer.start()
88
    Wflag = 1
89
    print("Turning on LED")
90
    #client.publish("sdk/test/cpp", 'ON', qos=1)
91
​
92
  elif (Message == 'OFF'):
93
    #ledOff()
94
    print ("Turning off LED")
95
    timer.cancel()
96
    publishOff()
97
    Wflag = 0
98
    #client.publish("sdk/test/cpp", 'OFF', qos=1)
99
​
100
client = paho.Client()
101
client.tls_set(root_ca,
102
                   certfile = public_crt,
103
                   keyfile = private_key,
104
                   cert_reqs = ssl.CERT_REQUIRED,
105
                   tls_version = ssl.PROTOCOL_TLSv1_2,
106
                   ciphers = None)
107
​
108
​
109
client.on_connect = on_connect
110
client.on_message = on_message
111
​
112
client.connect(mqtt_url, port = 8883, keepalive=60)
113
client.loop_start()
114
​
115
# Publish to the same topic in a loop forever                                                                           
116
loopCount = 0                                                                                                       
117
​
118
while True:
119
​
120
  if (Message == 'ON'):
121
​
122
      '''
123
                                                                                                       
124
      LineToNeutral = modclient.read_holding_registers(0x0F46, 2, unit=1)                                             
125
      decoder = BinaryPayloadDecoder.fromRegisters(LineToNeutral.registers, Endian.Big, wordorder=Endian.Little)
126
                                                                                                              
127
      Volt_val = float(decoder.decode_32bit_float())                                                                  
128
      print("Line To Neutral Voltage:", Volt_val)                                                                         
129
                                                                                                                    
130
      Frequency = modclient.read_holding_registers(0x0F4A, 2, unit=1)                                                    
131
      decoder = BinaryPayloadDecoder.fromRegisters(Frequency.registers, Endian.Big, wordorder=Endian.Little)          
132
                                                                                                                        
133
      Freq_val = float(decoder.decode_32bit_float())                                                               
134
      print("Frequency:", Freq_val)                                                                                                
135
      '''
136
      Freq_val = 49.906
137
      Volt_val = 230.507
138
      
139
      Watthour = modclient.read_holding_registers(0x009E, 2, unit=1)                                                
140
      decoder = BinaryPayloadDecoder.fromRegisters(Watthour.registers, Endian.Big, wordorder=Endian.Little)         
141
                                                                                                                         
142
      Wh_val = float(decoder.decode_32bit_float())
143
      kWh_val = Wh_val / 1000.0                                                                     
144
      print("kWh: ", kWh_val)
145
​
146
      if Wflag == 1:
147
        WhIn = Wh_val
148
        Wflag = 0
149
​
150
      print(WhIn, Wh_val, (Wh_val - WhIn))
151
      cost = (Wh_val - WhIn) * 0.2
152
                                                                                                                          
153
      print("==========================================================")                                        
154
                                                                                                               
155
                                                                                                                        
156
      #volt_val = str(LineToNeutral.registers)                                                                            
157
      #freq_val = str(Frequency.registers)                                                                                
158
​
159
      publishOn()                                                                                                                                                                                                                                                                      
160
      sleep(5)
161
​
162
​
163
  elif (Message == 'OFF'):
164
      
165
      Wflag = 0
166
​
167
  sleep(250/10000000.0)
168
​
Copied!
Step 3: Run the above code to read data from Energy Meter
python lg1119.py
Step 4: Visit the following website and check the live energy meter data
​https://ruggedboard.com/ev_demo/mqttSample/index.html​
If everything is correct your code will run without any error and you can see live the data to a AWS cloud and view it on a dashboard.

G3: How to Do? - Previous

Microsoft Azure on RB

Next - G4: Use Cases / Application Notes

IoT Based solution for Plants Water monitoring

Last modified 1yr ago

Copy link

Contents

Stage 1 : Testing ModDus Communication (RS485) using modpoll

Stage 2: Reading the Energy Meter values using Python 3 Script.

Stage 3: Reading the Energy meter values using Python 3 Script