How to send SMS by using PLC controller Arduino
Working with the GSM/GPRS SIM800L module in the Industrial Automation
6 May, 2021 by
How to send SMS by using PLC controller Arduino
Boot & Work Corp. S.L., Fernandez Queralt Martinez

Index

 
  1. Introduction

  2. Related links

  3. Requirements

  4. Insert the SIM Card

  5. Download the libraries

  6. Hardware test

 

Introduction


GSM (Global System for Global Communications) is the communication system most widely used in mobile phones, and its first functionality is the voice transmission. However, it also allows data transmission like SMS or Internet, at a very low speed.

GPRS (General Packet Radio Service) is an extension of GSM based on packet transmission that offers a more efficient service for data communications, especially in the case of Internet access.

So in this blog, you will learn how to test the GSM/GPRS SIM800L module of your Industrial GPRS family PLC Arduino.

Odoo text and image block

Related links

How to connect Raspberry PLC to Wi-Fi


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Basics about Raspberry Pi PLC analog outputs


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How to find your perfect industrial PLC


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How to program Raspberry PLC interrupt inputs with Python


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Raspberry PLC
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Requirements

Equipment

In order to work with the GPRS module, you will need any of our Industrial GPRS family Arduino industrial controller.

On this example, you will be working with the industrial Arduino based PLCs, highly used in the industrial automation Open Source projects.

The SIM800L module is the main component of the Adafruit FONA 800 cards so you can use the library made for these cards with the cheap modules that assemble the SIM800L. 

Insert the SIM card

You are going to proceed to insert the SIM card correctly into the programmable logic controller. To do this, you must first locate the SIM card inlet of the PLC, which is located on the top cover of your Arduino based PLC. You will be able to see the SIM card symbol in your Open Source Hardware, so insert the SIM card which is right under the symbol. 

Insert the SIM card

Download the libraries

Before testing your Arduino automation based PLC, you should download the following libraries. So let's follow the next steps:

1. Open the Arduino IDE.

2. In the menu, go to Tools.

3. Click on Manage Libraries...

4. Search "Adafruit FONA".

5. Finally, click on the Install button, to install de Adafruit FONA library.

Download the libraries

Hardware Test

Once the Adafruit FONA library is installed, let's proceed to test your Open Source hardware:

1. Open the File menu

2. Go to Examples

3. Go to Adafruit FONA Library

4. Click on FONAtest


A new sketch will open, and before testing it, you are going to do some changes to adapt it to your PLC:


If your GPRS/GSM PLC is a MDuino model: 

1. Look for the next three lines below and do the following:

REPLACE THIS:
#define FONA_RX 2 #define FONA_TX 3 #define FONA_RST 4

FOR THIS:
//#define FONA_RX 2 //#define FONA_TX 3 #define FONA_RST 2

2.  Uncomment and comment the following lines as so:

//#include <SoftwareSerial.h>
//SoftwareSerial fonaSS = SoftwareSerial(FONA_TX, FONA_RX);
//SoftwareSerial *fonaSerial = &fonaSS;

// Hardware serial is also possible!
  HardwareSerial *fonaSerial = &Serial1;


If your GPRS/GSM PLC is an Ardbox model:

1. Look for the next three lines below and do the following:

REPLACE THIS:
#define FONA_RX 2 #define FONA_TX 3 #define FONA_RST 4

FOR THIS:
#define FONA_RX MOSI #define FONA_TX MISO #define FONA_RST 2

2.  Uncomment and comment the following lines as so:

#include <SoftwareSerial.h>
SoftwareSerial fonaSS = SoftwareSerial(FONA_TX, FONA_RX);
SoftwareSerial *fonaSerial = &fonaSS;

// Hardware serial is also possible!
// HardwareSerial *fonaSerial = &Serial1;

The next steps can be followed with MDuino and Ardbox PLC models as well:

3. Uncomment the following line and add your credentials:

fona.setGPRSNetworkSettings(F("YOUR-APN-HERE"), F("YOUR-USER-HERE"), F("YOUR-PASSWORD-HERE"));

4. Finally, your code should look like this:

/***************************************************
  This is an example for our Adafruit FONA Cellular Module

  Designed specifically to work with the Adafruit FONA
  ----> http://www.adafruit.com/products/1946
  ----> http://www.adafruit.com/products/1963
  ----> http://www.adafruit.com/products/2468
  ----> http://www.adafruit.com/products/2542

  These cellular modules use TTL Serial to communicate, 2 pins are
  required to interface
  Adafruit invests time and resources providing this open source code,
  please support Adafruit and open-source hardware by purchasing
  products from Adafruit!

  Written by Limor Fried/Ladyada for Adafruit Industries.
  BSD license, all text above must be included in any redistribution
 ****************************************************/

/*
THIS CODE IS STILL IN PROGRESS!

Open up the serial console on the Arduino at 115200 baud to interact with FONA

Note that if you need to set a GPRS APN, username, and password scroll down to
the commented section below at the end of the setup() function.
*/
#include "Adafruit_FONA.h"

//#define FONA_RX 2
//#define FONA_TX 3
#define FONA_RST 2

// this is a large buffer for replies
char replybuffer[255];

// We default to using software serial. If you want to use hardware serial
// (because softserial isnt supported) comment out the following three lines 
// and uncomment the HardwareSerial line
//#include <SoftwareSerial.h>
//SoftwareSerial fonaSS = SoftwareSerial(FONA_TX, FONA_RX);
//SoftwareSerial *fonaSerial = &fonaSS;

// Hardware serial is also possible!
  HardwareSerial *fonaSerial = &Serial1;

// Use this for FONA 800 and 808s
Adafruit_FONA fona = Adafruit_FONA(FONA_RST);
// Use this one for FONA 3G
//Adafruit_FONA_3G fona = Adafruit_FONA_3G(FONA_RST);

uint8_t readline(char *buff, uint8_t maxbuff, uint16_t timeout = 0);

uint8_t type;

void setup() {
  while (!Serial);

  Serial.begin(115200);
  Serial.println(F("FONA basic test"));
  Serial.println(F("Initializing....(May take 3 seconds)"));

  fonaSerial->begin(4800);
  if (! fona.begin(*fonaSerial)) {
    Serial.println(F("Couldn't find FONA"));
    while (1);
  }
  type = fona.type();
  Serial.println(F("FONA is OK"));
  Serial.print(F("Found "));
  switch (type) {
    case FONA800L:
      Serial.println(F("FONA 800L")); break;
    case FONA800H:
      Serial.println(F("FONA 800H")); break;
    case FONA808_V1:
      Serial.println(F("FONA 808 (v1)")); break;
    case FONA808_V2:
      Serial.println(F("FONA 808 (v2)")); break;
    case FONA3G_A:
      Serial.println(F("FONA 3G (American)")); break;
    case FONA3G_E:
      Serial.println(F("FONA 3G (European)")); break;
    default: 
      Serial.println(F("???")); break;
  }
  
  // Print module IMEI number.
  char imei[16] = {0}; // MUST use a 16 character buffer for IMEI!
  uint8_t imeiLen = fona.getIMEI(imei);
  if (imeiLen > 0) {
    Serial.print("Module IMEI: "); Serial.println(imei);
  }

  // Optionally configure a GPRS APN, username, and password.
  // You might need to do this to access your network's GPRS/data
  // network.  Contact your provider for the exact APN, username,
  // and password values.  Username and password are optional and
  // can be removed, but APN is required.
  fona.setGPRSNetworkSettings(F("YOUR-APN-HERE"), F("YOUR-USER-HERE"), F("YOUR-PASSWORD-HERE"));

  // Optionally configure HTTP gets to follow redirects over SSL.
  // Default is not to follow SSL redirects, however if you uncomment
  // the following line then redirects over SSL will be followed.
  //fona.setHTTPSRedirect(true);

  printMenu();
}

void printMenu(void) {
  Serial.println(F("-------------------------------------"));
  Serial.println(F("[?] Print this menu"));
  Serial.println(F("[a] read the ADC 2.8V max (FONA800 & 808)"));
  Serial.println(F("[b] read the Battery V and % charged"));
  Serial.println(F("[C] read the SIM CCID"));
  Serial.println(F("[U] Unlock SIM with PIN code"));
  Serial.println(F("[i] read RSSI"));
  Serial.println(F("[n] get Network status"));
  Serial.println(F("[v] set audio Volume"));
  Serial.println(F("[V] get Volume"));
  Serial.println(F("[H] set Headphone audio (FONA800 & 808)"));
  Serial.println(F("[e] set External audio (FONA800 & 808)"));
  Serial.println(F("[T] play audio Tone"));
  Serial.println(F("[P] PWM/Buzzer out (FONA800 & 808)"));

  // FM (SIM800 only!)
  Serial.println(F("[f] tune FM radio (FONA800)"));
  Serial.println(F("[F] turn off FM (FONA800)"));
  Serial.println(F("[m] set FM volume (FONA800)"));
  Serial.println(F("[M] get FM volume (FONA800)"));
  Serial.println(F("[q] get FM station signal level (FONA800)"));

  // Phone
  Serial.println(F("[c] make phone Call"));
  Serial.println(F("[A] get call status"));
  Serial.println(F("[h] Hang up phone"));
  Serial.println(F("[p] Pick up phone"));

  // SMS
  Serial.println(F("[N] Number of SMSs"));
  Serial.println(F("[r] Read SMS #"));
  Serial.println(F("[R] Read All SMS"));
  Serial.println(F("[d] Delete SMS #"));
  Serial.println(F("[s] Send SMS"));
  Serial.println(F("[u] Send USSD"));
  
  // Time
  Serial.println(F("[y] Enable network time sync (FONA 800 & 808)"));
  Serial.println(F("[Y] Enable NTP time sync (GPRS FONA 800 & 808)"));
  Serial.println(F("[t] Get network time"));

  // GPRS
  Serial.println(F("[G] Enable GPRS"));
  Serial.println(F("[g] Disable GPRS"));
  Serial.println(F("[l] Query GSMLOC (GPRS)"));
  Serial.println(F("[w] Read webpage (GPRS)"));
  Serial.println(F("[W] Post to website (GPRS)"));

  // GPS
  if ((type == FONA3G_A) || (type == FONA3G_E) || (type == FONA808_V1) || (type == FONA808_V2)) {
    Serial.println(F("[O] Turn GPS on (FONA 808 & 3G)"));
    Serial.println(F("[o] Turn GPS off (FONA 808 & 3G)"));
    Serial.println(F("[L] Query GPS location (FONA 808 & 3G)"));
    if (type == FONA808_V1) {
      Serial.println(F("[x] GPS fix status (FONA808 v1 only)"));
    }
    Serial.println(F("[E] Raw NMEA out (FONA808)"));
  }
  
  Serial.println(F("[S] create Serial passthru tunnel"));
  Serial.println(F("-------------------------------------"));
  Serial.println(F(""));

}
void loop() {
  Serial.print(F("FONA> "));
  while (! Serial.available() ) {
    if (fona.available()) {
      Serial.write(fona.read());
    }
  }

  char command = Serial.read();
  Serial.println(command);


  switch (command) {
    case '?': {
        printMenu();
        break;
      }

    case 'a': {
        // read the ADC
        uint16_t adc;
        if (! fona.getADCVoltage(&adc)) {
          Serial.println(F("Failed to read ADC"));
        } else {
          Serial.print(F("ADC = ")); Serial.print(adc); Serial.println(F(" mV"));
        }
        break;
      }

    case 'b': {
        // read the battery voltage and percentage
        uint16_t vbat;
        if (! fona.getBattVoltage(&vbat)) {
          Serial.println(F("Failed to read Batt"));
        } else {
          Serial.print(F("VBat = ")); Serial.print(vbat); Serial.println(F(" mV"));
        }


        if (! fona.getBattPercent(&vbat)) {
          Serial.println(F("Failed to read Batt"));
        } else {
          Serial.print(F("VPct = ")); Serial.print(vbat); Serial.println(F("%"));
        }

        break;
      }

    case 'U': {
        // Unlock the SIM with a PIN code
        char PIN[5];
        flushSerial();
        Serial.println(F("Enter 4-digit PIN"));
        readline(PIN, 3);
        Serial.println(PIN);
        Serial.print(F("Unlocking SIM card: "));
        if (! fona.unlockSIM(PIN)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("OK!"));
        }
        break;
      }

    case 'C': {
        // read the CCID
        fona.getSIMCCID(replybuffer);  // make sure replybuffer is at least 21 bytes!
        Serial.print(F("SIM CCID = ")); Serial.println(replybuffer);
        break;
      }

    case 'i': {
        // read the RSSI
        uint8_t n = fona.getRSSI();
        int8_t r;

        Serial.print(F("RSSI = ")); Serial.print(n); Serial.print(": ");
        if (n == 0) r = -115;
        if (n == 1) r = -111;
        if (n == 31) r = -52;
        if ((n >= 2) && (n <= 30)) {
          r = map(n, 2, 30, -110, -54);
        }
        Serial.print(r); Serial.println(F(" dBm"));

        break;
      }

    case 'n': {
        // read the network/cellular status
        uint8_t n = fona.getNetworkStatus();
        Serial.print(F("Network status "));
        Serial.print(n);
        Serial.print(F(": "));
        if (n == 0) Serial.println(F("Not registered"));
        if (n == 1) Serial.println(F("Registered (home)"));
        if (n == 2) Serial.println(F("Not registered (searching)"));
        if (n == 3) Serial.println(F("Denied"));
        if (n == 4) Serial.println(F("Unknown"));
        if (n == 5) Serial.println(F("Registered roaming"));
        break;
      }

    /*** Audio ***/
    case 'v': {
        // set volume
        flushSerial();
        if ( (type == FONA3G_A) || (type == FONA3G_E) ) {
          Serial.print(F("Set Vol [0-8] "));
        } else {
          Serial.print(F("Set Vol % [0-100] "));
        }
        uint8_t vol = readnumber();
        Serial.println();
        if (! fona.setVolume(vol)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("OK!"));
        }
        break;
      }

    case 'V': {
        uint8_t v = fona.getVolume();
        Serial.print(v);
        if ( (type == FONA3G_A) || (type == FONA3G_E) ) {
          Serial.println(" / 8");
        } else {
          Serial.println("%");
        }
        break;
      }

    case 'H': {
        // Set Headphone output
        if (! fona.setAudio(FONA_HEADSETAUDIO)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("OK!"));
        }
        fona.setMicVolume(FONA_HEADSETAUDIO, 15);
        break;
      }
    case 'e': {
        // Set External output
        if (! fona.setAudio(FONA_EXTAUDIO)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("OK!"));
        }

        fona.setMicVolume(FONA_EXTAUDIO, 10);
        break;
      }

    case 'T': {
        // play tone
        flushSerial();
        Serial.print(F("Play tone #"));
        uint8_t kittone = readnumber();
        Serial.println();
        // play for 1 second (1000 ms)
        if (! fona.playToolkitTone(kittone, 1000)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("OK!"));
        }
        break;
      }

    /*** FM Radio ***/

    case 'f': {
        // get freq
        flushSerial();
        Serial.print(F("FM Freq (eg 1011 == 101.1 MHz): "));
        uint16_t station = readnumber();
        Serial.println();
        // FM radio ON using headset
        if (fona.FMradio(true, FONA_HEADSETAUDIO)) {
          Serial.println(F("Opened"));
        }
        if (! fona.tuneFMradio(station)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("Tuned"));
        }
        break;
      }
    case 'F': {
        // FM radio off
        if (! fona.FMradio(false)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("OK!"));
        }
        break;
      }
    case 'm': {
        // Set FM volume.
        flushSerial();
        Serial.print(F("Set FM Vol [0-6]:"));
        uint8_t vol = readnumber();
        Serial.println();
        if (!fona.setFMVolume(vol)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("OK!"));
        }
        break;
      }
    case 'M': {
        // Get FM volume.
        uint8_t fmvol = fona.getFMVolume();
        if (fmvol < 0) {
          Serial.println(F("Failed"));
        } else {
          Serial.print(F("FM volume: "));
          Serial.println(fmvol, DEC);
        }
        break;
      }
    case 'q': {
        // Get FM station signal level (in decibels).
        flushSerial();
        Serial.print(F("FM Freq (eg 1011 == 101.1 MHz): "));
        uint16_t station = readnumber();
        Serial.println();
        int8_t level = fona.getFMSignalLevel(station);
        if (level < 0) {
          Serial.println(F("Failed! Make sure FM radio is on (tuned to station)."));
        } else {
          Serial.print(F("Signal level (dB): "));
          Serial.println(level, DEC);
        }
        break;
      }

    /*** PWM ***/

    case 'P': {
        // PWM Buzzer output @ 2KHz max
        flushSerial();
        Serial.print(F("PWM Freq, 0 = Off, (1-2000): "));
        uint16_t freq = readnumber();
        Serial.println();
        if (! fona.setPWM(freq)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("OK!"));
        }
        break;
      }

    /*** Call ***/
    case 'c': {
        // call a phone!
        char number[30];
        flushSerial();
        Serial.print(F("Call #"));
        readline(number, 30);
        Serial.println();
        Serial.print(F("Calling ")); Serial.println(number);
        if (!fona.callPhone(number)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("Sent!"));
        }

        break;
      }
    case 'A': {
        // get call status
        int8_t callstat = fona.getCallStatus();
        switch (callstat) {
          case 0: Serial.println(F("Ready")); break;
          case 1: Serial.println(F("Could not get status")); break;
          case 3: Serial.println(F("Ringing (incoming)")); break;
          case 4: Serial.println(F("Ringing/in progress (outgoing)")); break;
          default: Serial.println(F("Unknown")); break;
        }
        break;
      }
      
    case 'h': {
        // hang up!
        if (! fona.hangUp()) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("OK!"));
        }
        break;
      }

    case 'p': {
        // pick up!
        if (! fona.pickUp()) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("OK!"));
        }
        break;
      }

    /*** SMS ***/

    case 'N': {
        // read the number of SMS's!
        int8_t smsnum = fona.getNumSMS();
        if (smsnum < 0) {
          Serial.println(F("Could not read # SMS"));
        } else {
          Serial.print(smsnum);
          Serial.println(F(" SMS's on SIM card!"));
        }
        break;
      }
    case 'r': {
        // read an SMS
        flushSerial();
        Serial.print(F("Read #"));
        uint8_t smsn = readnumber();
        Serial.print(F("\n\rReading SMS #")); Serial.println(smsn);

        // Retrieve SMS sender address/phone number.
        if (! fona.getSMSSender(smsn, replybuffer, 250)) {
          Serial.println("Failed!");
          break;
        }
        Serial.print(F("FROM: ")); Serial.println(replybuffer);

        // Retrieve SMS value.
        uint16_t smslen;
        if (! fona.readSMS(smsn, replybuffer, 250, &smslen)) { // pass in buffer and max len!
          Serial.println("Failed!");
          break;
        }
        Serial.print(F("***** SMS #")); Serial.print(smsn);
        Serial.print(" ("); Serial.print(smslen); Serial.println(F(") bytes *****"));
        Serial.println(replybuffer);
        Serial.println(F("*****"));

        break;
      }
    case 'R': {
        // read all SMS
        int8_t smsnum = fona.getNumSMS();
        uint16_t smslen;
        int8_t smsn;

        if ( (type == FONA3G_A) || (type == FONA3G_E) ) {
          smsn = 0; // zero indexed
          smsnum--;
        } else {
          smsn = 1;  // 1 indexed
        }

        for ( ; smsn <= smsnum; smsn++) {
          Serial.print(F("\n\rReading SMS #")); Serial.println(smsn);
          if (!fona.readSMS(smsn, replybuffer, 250, &smslen)) {  // pass in buffer and max len!
            Serial.println(F("Failed!"));
            break;
          }
          // if the length is zero, its a special case where the index number is higher
          // so increase the max we'll look at!
          if (smslen == 0) {
            Serial.println(F("[empty slot]"));
            smsnum++;
            continue;
          }

          Serial.print(F("***** SMS #")); Serial.print(smsn);
          Serial.print(" ("); Serial.print(smslen); Serial.println(F(") bytes *****"));
          Serial.println(replybuffer);
          Serial.println(F("*****"));
        }
        break;
      }

    case 'd': {
        // delete an SMS
        flushSerial();
        Serial.print(F("Delete #"));
        uint8_t smsn = readnumber();

        Serial.print(F("\n\rDeleting SMS #")); Serial.println(smsn);
        if (fona.deleteSMS(smsn)) {
          Serial.println(F("OK!"));
        } else {
          Serial.println(F("Couldn't delete"));
        }
        break;
      }

    case 's': {
        // send an SMS!
        char sendto[21], message[141];
        flushSerial();
        Serial.print(F("Send to #"));
        readline(sendto, 20);
        Serial.println(sendto);
        Serial.print(F("Type out one-line message (140 char): "));
        readline(message, 140);
        Serial.println(message);
        if (!fona.sendSMS(sendto, message)) {
          Serial.println(F("Failed"));
        } else {
          Serial.println(F("Sent!"));
        }

        break;
      }

    case 'u': {
      // send a USSD!
      char message[141];
      flushSerial();
      Serial.print(F("Type out one-line message (140 char): "));
      readline(message, 140);
      Serial.println(message);

      uint16_t ussdlen;
      if (!fona.sendUSSD(message, replybuffer, 250, &ussdlen)) { // pass in buffer and max len!
        Serial.println(F("Failed"));
      } else {
        Serial.println(F("Sent!"));
        Serial.print(F("***** USSD Reply"));
        Serial.print(" ("); Serial.print(ussdlen); Serial.println(F(") bytes *****"));
        Serial.println(replybuffer);
        Serial.println(F("*****"));
      }
    }

    /*** Time ***/

    case 'y': {
        // enable network time sync
        if (!fona.enableNetworkTimeSync(true))
          Serial.println(F("Failed to enable"));
        break;
      }

    case 'Y': {
        // enable NTP time sync
        if (!fona.enableNTPTimeSync(true, F("pool.ntp.org")))
          Serial.println(F("Failed to enable"));
        break;
      }

    case 't': {
        // read the time
        char buffer[23];

        fona.getTime(buffer, 23);  // make sure replybuffer is at least 23 bytes!
        Serial.print(F("Time = ")); Serial.println(buffer);
        break;
      }


    /*********************************** GPS (SIM808 only) */

    case 'o': {
        // turn GPS off
        if (!fona.enableGPS(false))
          Serial.println(F("Failed to turn off"));
        break;
      }
    case 'O': {
        // turn GPS on
        if (!fona.enableGPS(true))
          Serial.println(F("Failed to turn on"));
        break;
      }
    case 'x': {
        int8_t stat;
        // check GPS fix
        stat = fona.GPSstatus();
        if (stat < 0)
          Serial.println(F("Failed to query"));
        if (stat == 0) Serial.println(F("GPS off"));
        if (stat == 1) Serial.println(F("No fix"));
        if (stat == 2) Serial.println(F("2D fix"));
        if (stat == 3) Serial.println(F("3D fix"));
        break;
      }

    case 'L': {
        // check for GPS location
        char gpsdata[120];
        fona.getGPS(0, gpsdata, 120);
        if (type == FONA808_V1)
          Serial.println(F("Reply in format: mode,longitude,latitude,altitude,utctime(yyyymmddHHMMSS),ttff,satellites,speed,course"));
        else 
          Serial.println(F("Reply in format: mode,fixstatus,utctime(yyyymmddHHMMSS),latitude,longitude,altitude,speed,course,fixmode,reserved1,HDOP,PDOP,VDOP,reserved2,view_satellites,used_satellites,reserved3,C/N0max,HPA,VPA"));
        Serial.println(gpsdata);

        break;
      }

    case 'E': {
        flushSerial();
        if (type == FONA808_V1) {
          Serial.print(F("GPS NMEA output sentences (0 = off, 34 = RMC+GGA, 255 = all)"));
        } else {
          Serial.print(F("On (1) or Off (0)? "));
        }
        uint8_t nmeaout = readnumber();

        // turn on NMEA output
        fona.enableGPSNMEA(nmeaout);

        break;
      }

    /*********************************** GPRS */

    case 'g': {
        // turn GPRS off
        if (!fona.enableGPRS(false))
          Serial.println(F("Failed to turn off"));
        break;
      }
    case 'G': {
        // turn GPRS on
        if (!fona.enableGPRS(true))
          Serial.println(F("Failed to turn on"));
        break;
      }
    case 'l': {
        // check for GSMLOC (requires GPRS)
        uint16_t returncode;

        if (!fona.getGSMLoc(&returncode, replybuffer, 250))
          Serial.println(F("Failed!"));
        if (returncode == 0) {
          Serial.println(replybuffer);
        } else {
          Serial.print(F("Fail code #")); Serial.println(returncode);
        }

        break;
      }
    case 'w': {
        // read website URL
        uint16_t statuscode;
        int16_t length;
        char url[80];

        flushSerial();
        Serial.println(F("NOTE: in beta! Use small webpages to read!"));
        Serial.println(F("URL to read (e.g. wifitest.adafruit.com/testwifi/index.html):"));
        Serial.print(F("http://")); readline(url, 79);
        Serial.println(url);

        Serial.println(F("****"));
        if (!fona.HTTP_GET_start(url, &statuscode, (uint16_t *)&length)) {
          Serial.println("Failed!");
          break;
        }
        while (length > 0) {
          while (fona.available()) {
            char c = fona.read();

            // Serial.write is too slow, we'll write directly to Serial register!
#if defined(__AVR_ATmega328P__) || defined(__AVR_ATmega168__)
            loop_until_bit_is_set(UCSR0A, UDRE0); /* Wait until data register empty. */
            UDR0 = c;
#else
            Serial.write(c);
#endif
            length--;
            if (! length) break;
          }
        }
        Serial.println(F("\n****"));
        fona.HTTP_GET_end();
        break;
      }

    case 'W': {
        // Post data to website
        uint16_t statuscode;
        int16_t length;
        char url[80];
        char data[80];

        flushSerial();
        Serial.println(F("NOTE: in beta! Use simple websites to post!"));
        Serial.println(F("URL to post (e.g. httpbin.org/post):"));
        Serial.print(F("http://")); readline(url, 79);
        Serial.println(url);
        Serial.println(F("Data to post (e.g. \"foo\" or \"{\"simple\":\"json\"}\"):"));
        readline(data, 79);
        Serial.println(data);

        Serial.println(F("****"));
        if (!fona.HTTP_POST_start(url, F("text/plain"), (uint8_t *) data, strlen(data), &statuscode, (uint16_t *)&length)) {
          Serial.println("Failed!");
          break;
        }
        while (length > 0) {
          while (fona.available()) {
            char c = fona.read();

#if defined(__AVR_ATmega328P__) || defined(__AVR_ATmega168__)
            loop_until_bit_is_set(UCSR0A, UDRE0); /* Wait until data register empty. */
            UDR0 = c;
#else
            Serial.write(c);
#endif

            length--;
            if (! length) break;
          }
        }
        Serial.println(F("\n****"));
        fona.HTTP_POST_end();
        break;
      }
    /*****************************************/

    case 'S': {
        Serial.println(F("Creating SERIAL TUBE"));
        while (1) {
          while (Serial.available()) {
            delay(1);
            fona.write(Serial.read());
          }
          if (fona.available()) {
            Serial.write(fona.read());
          }
        }
        break;
      }

    default: {
        Serial.println(F("Unknown command"));
        printMenu();
        break;
      }
  }
  // flush input
  flushSerial();
  while (fona.available()) {
    Serial.write(fona.read());
  }

}

void flushSerial() {
  while (Serial.available())
    Serial.read();
}

char readBlocking() {
  while (!Serial.available());
  return Serial.read();
}
uint16_t readnumber() {
  uint16_t x = 0;
  char c;
  while (! isdigit(c = readBlocking())) {
    //Serial.print(c);
  }
  Serial.print(c);
  x = c - '0';
  while (isdigit(c = readBlocking())) {
    Serial.print(c);
    x *= 10;
    x += c - '0';
  }
  return x;
}

uint8_t readline(char *buff, uint8_t maxbuff, uint16_t timeout) {
  uint16_t buffidx = 0;
  boolean timeoutvalid = true;
  if (timeout == 0) timeoutvalid = false;

  while (true) {
    if (buffidx > maxbuff) {
      //Serial.println(F("SPACE"));
      break;
    }

    while (Serial.available()) {
      char c =  Serial.read();

      //Serial.print(c, HEX); Serial.print("#"); Serial.println(c);

      if (c == '\r') continue;
      if (c == 0xA) {
        if (buffidx == 0)   // the first 0x0A is ignored
          continue;

        timeout = 0;         // the second 0x0A is the end of the line
        timeoutvalid = true;
        break;
      }
      buff[buffidx] = c;
      buffidx++;
    }

    if (timeoutvalid && timeout == 0) {
      //Serial.println(F("TIMEOUT"));
      break;
    }
    delay(1);
  }
  buff[buffidx] = 0;  // null term
  return buffidx;
}


5. To upload the FONAtest sketch, you should have the Industrial Shields board already installed. So, if you still do not have them, please follow the next steps:

https://www.industrialshields.com/blog/arduino-industrial-1/post/how-to-install-industrial-shields-boards-in-the-arduino-ide-63

6. Then, go to Tools menu >> Boards >> Industrial Shields Boards >> And select your device family. In this case, as you are using a the M-Duino 19R+ GPRS, you should select M-Duino Family.

7. To select the model, go the Tools menu >> Model >> M-Duino 19R+, or the Industrial Shields model you are using.

8. Finally, in the same menu, go the Port tab, and select the Port you are using to connect your Arduino based controller.

9. Once everything is ready, first click on the magnifying glass icon to compile, and then the arrow button to upload the sketch.

10. Click on the magnifying glass button to open up the Serial Monitor. Select the Both NL & CR option, which is NewLine and Carriage return, or \n\r. And also the baudrate to 115200.

11. So now, you are ready to test your Open source hardware. In the Serial monitor, you will see that the following menu will appear:



12. To enable the GPRS, lets type a "G" letter in the top bar of Arduino IDE Serial monitor, and click on Send. You will be able to check if everything was fine, as in the picture below, or if you got any error. 

How to test GPRS in Arduino based PLCs


13. To send a SMS from your Arduino based PLC to our phone  type the "s" option. Type your phone number, and then the message you want to send. In our case: "Hello, This is the Arduino based PLC with GPRS :)"

How to test GPRS in Arduino based PLCs



Finally, you will get the SMS message to your phone!

How to test GPRS in Arduino based PLCs


How to send SMS by using PLC controller Arduino
Boot & Work Corp. S.L., Fernandez Queralt Martinez
6 May, 2021
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