server/clock-server-json/main.cpp

#include <ctime>
#include <csignal>
#include <thread>
#include <iostream>
#include <modbuspp.h>
#include <modbuspp/popl.h>

using namespace std;
using namespace Modbus;

const int SlaveAddress = 10;

Server srv; // instantiates new MODBUS Server

// -----------------------------------------------------------------------------
// Signal trap, triggers during a CTRL+C or if kill is called
void
sighandler (int sig) {

  srv.close();
  cout << "everything was closed." << endl << "Have a nice day !" << endl;
  exit(EXIT_SUCCESS);
}

// -----------------------------------------------------------------------------
int main (int argc, char **argv) {

  if (argc < 2) {

    cerr << "Error: the JSON filename must be provided as a parameter on the command line !" << endl;
    cerr << "e.g. : " << argv[0] << " clock-server-tcp.json" << endl;
    exit (EXIT_FAILURE);
  }

  string  jsonfile = argv[1];
  time_t now, before;
  tm * t;

  // ModBus Data
  bool daylight;// daylight saving time, true = summer time
  Data<int32_t> gmtoff; // GMT offset, +/- minutes, Big endian order : ABCD
  uint16_t mb_time[8]; // date and time

  cout << "Modbus Time Server" << endl;
  // CTRL+C and kill call triggers the trap sighandler()
  signal (SIGINT, sighandler);
  signal (SIGTERM, sighandler);
  cout << "Press CTRL+C to stop... " << endl << endl;

  try {
    cout << "opening " << jsonfile << "..." << endl;
    srv.setConfig (jsonfile, "modbuspp-server");

    BufferedSlave & slv = srv.slave (SlaveAddress); // Adding a new slave to the server
    cout << "Slave id: " << slv.number() << endl;
    if (srv.debug()) {
      cout << "Mapping of registers:" << endl
           << "--- Input Registers" << endl
           << "@ Reg.  Size    Description" << endl
           << "1       16-bit  Seconds (0-60), unsigned" << endl
           << "2       16-bit  Minutes (0-59), unsigned" << endl
           << "3       16-bit  Hours (0-23), unsigned" << endl
           << "4       16-bit  Day of the month (1-31), unsigned" << endl
           << "5       16-bit  Month (1-12), unsigned" << endl
           << "6       16-bit  Year e.g. 2019, unsigned" << endl
           << "7       16-bit  Day of the week (0-6, Sunday = 0), unsigned" << endl
           << "8       16-bit  Day in the year (1-366, 1 Jan = 1), unsigned" << endl
           << "--- Holding Registers" << endl
           << "@ Reg.  Size    Description" << endl
           << "1       32-bit  number of seconds to add to UTC to get local time, signed" << endl
           << "--- Coils" << endl
           << "@ Reg.  Size    Description" << endl
           << "1       1-bit   Daylight saving time" << endl << endl;
    }

    now = before = time (nullptr);
    t = localtime (&now);

    // init tz_offset and daylight saving time from from localtime
    daylight = (t->tm_isdst > 0);
    slv.writeCoil (1, daylight);

    gmtoff = t->tm_gmtoff;
    slv.writeRegister (1, gmtoff);

    if (srv.open ()) { // open a connection
      cout << "Listening server on " <<
           srv.connection() << ":" << srv.settings() << "..." << endl << endl;

      do {

        now = time (nullptr);

        if (now > before) {

          before = now;

          // update daylight saving time from holding register
          slv.readCoil (1, daylight);

          // update GMT offset from holding register
          slv.readRegister (1, gmtoff);

          // calculate the epoch time
          now += (daylight ? 3600 : 0) + gmtoff;

          t = gmtime (&now);
          mb_time[0] = t->tm_sec;
          mb_time[1] = t->tm_min;
          mb_time[2] = t->tm_hour;
          mb_time[3] = t->tm_mday;
          mb_time[4] = t->tm_mon + 1;
          mb_time[5] = t->tm_year + 1900;
          mb_time[6] = t->tm_wday;
          mb_time[7] = t->tm_yday + 1;

          // update the input registers
          slv.writeInputRegisters (1, mb_time, 8);
        }

        srv.poll (100);
      }
      while (srv.isOpen());
    }
  }
  catch (std::exception & e) {

    cerr << "Error: " << e.what() << endl;
  }
  catch (...) {

    cerr << "Unattended exception !" << endl;
  }

  return EXIT_FAILURE;
}
/* ========================================================================== */