/*
  Ethernet Modbus TCP Client Toggle

  This sketch toggles the coil of a Modbus TCP server connected
  on and off every second.

  Circuit:
   - Any Arduino MKR Board
   - MKR ETH Shield

  created 16 July 2018
  by Sandeep Mistry
*/

#include <SPI.h>
#include <Ethernet.h>

#include <ArduinoRS485.h> // ArduinoModbus depends on the ArduinoRS485 library
#include <ArduinoModbus.h>

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
// The IP address will be dependent on your local network:
byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
IPAddress ip(192, 168, 1, 177);

EthernetClient ethClient;
ModbusTCPClient modbusTCPClient(ethClient);

IPAddress server(192, 168, 1, 10); // update with the IP Address of your Modbus server

void setup() {
  //Initialize serial and wait for port to open:
  Serial.begin(9600);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }

  // start the Ethernet connection and the server:
  Ethernet.begin(mac, ip);

  // Check for Ethernet hardware present
  if (Ethernet.hardwareStatus() == EthernetNoHardware) {
    Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
    while (true) {
      delay(1); // do nothing, no point running without Ethernet hardware
    }
  }
  if (Ethernet.linkStatus() == LinkOFF) {
    Serial.println("Ethernet cable is not connected.");
  }
}

void loop() {
  if (!modbusTCPClient.connected()) {
    // client not connected, start the Modbus TCP client
    Serial.println("Attempting to connect to Modbus TCP server");
    
    if (!modbusTCPClient.begin(server, 502)) {
      Serial.println("Modbus TCP Client failed to connect!");
    } else {
      Serial.println("Modbus TCP Client connected");
    }
  } else {
    // client connected

    // write the value of 0x01, to the coil at address 0x00
    if (!modbusTCPClient.coilWrite(0x00, 0x01)) {
      Serial.print("Failed to write coil! ");
      Serial.println(modbusTCPClient.lastError());
    }

    // wait for 1 second
    delay(1000);

    // write the value of 0x00, to the coil at address 0x00
    if (!modbusTCPClient.coilWrite(0x00, 0x00)) {
      Serial.print("Failed to write coil! ");
      Serial.println(modbusTCPClient.lastError());
    }

    // wait for 1 second
    delay(1000);
  }
}