The next step is to\nconnect the sensors to the arduino microcontroller. We will use the\nSoftwareSerial library to allow serial communication on other digital pins of\nthe Arduino and be able to read more than one serial device. So, the RX and TX\nterminals of first sensor are connected to the pins 11 and 10 of the\nmicrocontroller and the RX and TX terminals of second sensor are connected to\nthe pins 13 and 12 respectively.<\/p>\n\n\n\n
Now, it is time to develop the code in Arduino IDE as follows:<\/p>\n\n\n\n
\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\n \/\/* Code to get the voltage, current and power from two AC PZEM sensors connected to the Arduino Mega microcontroller, then all the values *\/\/\n \/\/ are concatenated in one char variable in order to send it through serial communication \/\/ \n \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\n \n #include \n #include \n \n IPAddress ip(192,168,1,11);\n IPAddress ip1(192,168,1,10);\n \n char ix[10];\n char iy[10];\n char iz[10];\n char conc[360];\n \n char ix1[10];\n char iy1[10];\n char iz1[10];\n \n float V, V1;\n float i, i1;\n float p, p1;\n \n void setup() {\n Serial.begin (9600);\n }\n \n void loop() {\n \n PZEM004T pzem(10,11); \/\/(RX TX)\n pzem.setAddress (ip);\n V=pzem.voltage(ip); \/\/voltage obtained from the pzem library\n i = pzem.current(ip); \/\/current obtained from the pzem library\n p = pzem.power(ip);\/\/power obtained from the pzem library\n dtostrf(V,7,3,ix); \/\/function used to stored the current value in the char variable ix, specifying 3 as the number of digits after the point\n dtostrf(i,7,3,iy); \/\/function used to stored the current value in the char variable iy, specifying 3 as the number of digits after the point\n dtostrf(p,7,3,iz); \/\/function used to stored the power value in the char variable iz, specifying 3 as the number of digits after the point\n delay(1000);\n \n PZEM004T pzem1(12,13); \/\/(RX TX)\n pzem1.setAddress (ip1);\n V1=pzem1.voltage(ip1); \/\/voltage obtained from the pzem library\n i1 = pzem1.current(ip1); \/\/current obtained from the pzem library\n p1 = pzem1.power(ip1);\/\/power obtained from the pzem library\n dtostrf(V1,7,3,ix1);\/\/function used to stored the current value in the char variable ix1, specifying 3 as the number of digits after the point\n dtostrf(i1,7,3,iy1); \/\/function used to stored the current value in the char variable iy1, specifying 3 as the number of digits after the point\n dtostrf(p1,7,3,iz1); \/\/function used to stored the power value in the char variable iz1, specifying 3 as the number of digits after the point\n delay(1000);\n \n sprintf(conc,\": %s, : %s, : %s, : %s, : %s, : %s,\\n\", ix,iy,iz,ix1,iy1,iz1); \/\/ function used to concatenate all the values in one unique char variable \n Serial.write(conc);\n \n } <\/pzem004t.h><\/softwareserial.h><\/pre>\n\n\n\nRemarks:<\/strong><\/p>\n\n\n\n The sensors are not read at the same time. <\/li> The type of the values given by the sensor is float. <\/li> After getting all the values these are converted from float to char type by using the \u201cdtostrf\u201d function in which the decimal places are limited to three. <\/li> All the 6 values are concatenated, using the function \u201csprintf\u201d, in one unique char array and then it is sent as serial data. <\/li> Besides putting all the values together in the char array, we also put the \u2018:\u2019 and \u2018,\u2019 characters. In the end, the char array looks like: \u201c: val1, : val2, : val3, : val4, : val5, : val6, :\u201d. It is done in order to analyze and get the values easily in python. <\/li><\/ul>\n\n\n\nAfter uploading and testing\nthe code on the microcontroller, it is time to deal with the python script. The\nArduino microcontroller should be connected to the Raspberry by using a USB\ncable.<\/p>\n\n\n\n
Before starting with the\ncode, it could be good to know how to create a python file from the Linux\nterminal. It is done by typing the next command line:<\/p>\n\n\n\n
touch PZEM_Sensors.py <\/strong><\/p>\n\n\n\nThen to open the\nfile already created, we should type the next command line:<\/p>\n\n\n\n
nano PZEM_Sensors.py<\/strong><\/p>\n\n\n\nThe next screen will appear:<\/p>\n\n\n\nSo now, let\u2019s take a look at the code:<\/p>\n\n\n\n
import serial\n import time\n import re\n \n port = \"\/dev\/ttyACM0\"\n s1 = serial.Serial(port,9600)\n \n while True:\n if s1.inWaiting()>0:\n inputValue = s1.readline().decode() \n m = re.search('.*:(.*),.*:(.*),.*:(.*),.*:(.*),.*:(.*),.*:(.*),',inputValue) # command used to read the information and split it between the charcaters ':' and ','\n v1 = m.group(1).replace(\" \",\"\") ## command used to saved the information splitted before in a the variable \n i1 = m.group(2).replace(\" \",\"\")\n p1 = m.group(3).replace(\" \",\"\")\n v2 = m.group(4).replace(\" \",\"\")\n i2 = m.group(5).replace(\" \",\"\")\n p2 = m.group(6).replace(\" \",\"\")\n a = float(v1)\n b = float(i1)\n c = float(p1)\n d = float(v2)\n e = float(i2)\n f = float(p2)\n print(\"Voltage1:\",+a)\n print(\"Current1:\",+b)\n print(\"Power1:\",+c)\n print(\"Voltage2:\",+d)\n print(\"Current2:\",+e)\n print(\"Power2:\",+f) <\/pre>\n\n\n\nRemarks:<\/strong><\/p>\n\n\n\n We should specify the port of the Raspberry where the sensor is connected to. To know it, we should just type the next command from the LX Terminal window: ls \/dev –> The names of the connected USB devices start with: \u201cttyUSBX\u201d. Where X indicates the number of each USB device connected. <\/li> The serial port is read and decoded to make sure we have a string of chars. It is done with the function readline() and decode() respectively. <\/li> All the six values are getting by using regular expressions. Using \u2018.*:(.*),\u2019, we take all the characters which are between \u2018:\u2019 and \u2018,\u2019 and then they are stored in groups. <\/li> In the end the values are converted from char to float type. <\/li><\/ul>\n\n\n\nAfter writing all\nthe code and pressing the keys Ctrl + X you will be asked to save it or not.\nYou should press the key y or n and then Enter.<\/p>\n\n\n\n
To run the code, we should type the next command line:<\/p>\n\n\n\n
python PZEM_Sensors.py <\/strong><\/p>\n\n\n\nThen all the results\nand messages will appear in the Terminal windows or a message of error will\nappear if something wrong is inside the code.<\/p>\n\n\n\n
The figure below shows all the results got from the two PZEM sensors. The current 1 is 0 due to there is not any current sensor connected to and for that the reason the power 1 is also 0. If there is any problem of communication the value, we will get is -1.<\/p>\n\n\n\nI hope this tutorial can help you, <\/p>\n\n\n\n
Best regards, <\/p>\n\n\n\n
Richard Flores Diaz<\/p>\n","protected":false},"excerpt":{"rendered":"
Hi everyone, Today and for the end of my internship, i propose this tutorial to connect raspberry pi and 2…<\/p>\n","protected":false},"author":6,"featured_media":590,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[54],"tags":[82],"class_list":["post-581","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-capteurs","tag-capteurs"],"_links":{"self":[{"href":"https:\/\/miniprojets.net\/index.php\/wp-json\/wp\/v2\/posts\/581","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/miniprojets.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/miniprojets.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/miniprojets.net\/index.php\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/miniprojets.net\/index.php\/wp-json\/wp\/v2\/comments?post=581"}],"version-history":[{"count":0,"href":"https:\/\/miniprojets.net\/index.php\/wp-json\/wp\/v2\/posts\/581\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/miniprojets.net\/index.php\/wp-json\/wp\/v2\/media\/590"}],"wp:attachment":[{"href":"https:\/\/miniprojets.net\/index.php\/wp-json\/wp\/v2\/media?parent=581"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/miniprojets.net\/index.php\/wp-json\/wp\/v2\/categories?post=581"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/miniprojets.net\/index.php\/wp-json\/wp\/v2\/tags?post=581"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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