How to create a webserver to read an SD card with our Ethernet PLC Arduino

In this example, we can see how to create a webserver to read an SD card into the PLC through an Ethernet connection for industrial automation. We will show how to create a server that when there is a request through a browser, you will see the directories and the files of the SD card.

Follow this post to ensure a good connection of the SD Card on the Ethernet Programmable Logic Controller Arduino.

Arduino sd card  Arduino sd card   Arduino sd card     

Requirements

Ethernet PLC industrial controller

   M-Duino Family Products

   ESP32 Family Products

ESP32 web server sd card
Arduino SD Library

  Arduino SD Library

ESP32 web server sd card   Arduino automation

Software

Once all is connected correctly, the next step is to make the right configuration of the Ethernet port and create the server:

/*
   Copyright (c) 2017 Boot&Work Corp., S.L. All rights reserved

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <SD.h>
#include <Ethernet2.h>


#define SD_SS_PIN 53


File root;

// Enter a MAC address for your controller below. The MAC can be defined by yourself following the MAC standard structure rules. 
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
EthernetServer server(80);

/////////////////////////////////////////////////////////////////////////////////
void setup() {
	Serial.begin(115200L);

  // Init Ethernet and TCP server
  Serial.println("Starting Ethernet ...");
  Ethernet.begin(mac);
  server.begin();

  // Init SD card
  Serial.println("Starting SD card ...");
  if (!SD.begin(SD_SS_PIN)) {
    Serial.println("initialization failed!");
    return;
  }

  Serial.print("IP address: ");
  Serial.println(Ethernet.localIP());
}

///////////////////////////////////////////////////////////////////////////////
void loop() {
  EthernetClient client = server.available();
  if (client) {
    char lastC = 0;
    while (client.connected()) {
      if (client.available()) {
        char c = client.read();
        if ((c == '\n') && (lastC == '\n')) {
          client.println("HTTP/1.1 200 OK");
          client.println("Content-Type: text/plain");
          client.println("Connection: close");
          client.println();
          client.println("SD card files:");

          root = SD.open("/");
          printDirectory(root, client);

          break;
        }
        if (c != '\r') {
          lastC = c;
        }
      }
    }
    delay(50);
    client.stop();
  }
}

////////////////////////////////////////////////////////////////////////////////
void printDirectory(File dir, Stream &stream) {
  while (true) {
    File entry = dir.openNextFile();
    if (!entry) {
      // no more files
      break;
    }

    stream.print(entry.name());
    if (entry.isDirectory()) {
      stream.println("/");
    } else {
      // files have sizes, directories do not
      stream.print(" [");
      stream.print(entry.size(), DEC);
      stream.println("]");
    }
    entry.close();
  }
}