libmodbus_client.cpp

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/*
 * Copyright (c) 2018 Pilz GmbH & Co. KG
 *
 * 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 <ros/ros.h>

#include <cstddef>
#include <vector>
#include <errno.h>
#include <limits>
#include <stdexcept>

#include <prbt_hardware_support/libmodbus_client.h>
#include <prbt_hardware_support/pilz_modbus_exceptions.h>

namespace prbt_hardware_support
{

LibModbusClient::~LibModbusClient()
{
  close();
}

bool LibModbusClient::init(const char* ip, unsigned int port)
{
  modbus_connection_ = modbus_new_tcp(ip, port);

  if (modbus_connect(modbus_connection_) == -1)
  {
    ROS_ERROR_STREAM_NAMED("LibModbusClient", "Could not establish modbus connection." << modbus_strerror(errno));
    modbus_free(modbus_connection_);
    modbus_connection_ = nullptr;
    return false;
  }
  return true;
}

void LibModbusClient::setResponseTimeoutInMs(unsigned long timeout_ms)
{
  struct timeval response_timeout;
  response_timeout.tv_sec = timeout_ms/1000;
  response_timeout.tv_usec = (timeout_ms % 1000) * 1000;
  modbus_set_response_timeout(modbus_connection_, &response_timeout);
}

unsigned long LibModbusClient::getResponseTimeoutInMs()
{
  struct timeval response_timeout;
  modbus_get_response_timeout(modbus_connection_, &response_timeout);
  return response_timeout.tv_sec * 1000L + (response_timeout.tv_usec  / 1000L);
}

RegCont LibModbusClient::readHoldingRegister(int addr, int nb)
{
  ROS_DEBUG("readHoldingRegister()");
  if(modbus_connection_ == nullptr)
  {
    throw ModbusExceptionDisconnect("Modbus disconnected!");
  }

  RegCont tab_reg(static_cast<RegCont::size_type>(nb));
  int rc {-1};

  rc = modbus_read_registers(modbus_connection_, addr, nb, tab_reg.data());
  if (rc == -1)
  {
    std::ostringstream errStream;
    errStream << "Failed to read " << nb;
    errStream << " registers starting from " << addr;
    errStream << " with err: " << modbus_strerror(errno);
    ROS_ERROR_STREAM_NAMED("LibModbusClient", errStream.str());
    throw ModbusExceptionDisconnect(errStream.str());
  }

  return tab_reg;
}

RegCont LibModbusClient::writeReadHoldingRegister(const int write_addr,
                                                  const RegCont& write_reg,
                                                  const int read_addr, const int read_nb)
{
  if(modbus_connection_ == nullptr)
  {
    throw ModbusExceptionDisconnect("Modbus disconnected!");
  }

  if (read_nb < 0)
  {
    throw std::invalid_argument("Argument \"read_nb\" must not be negative");
  }
  RegCont read_reg(static_cast<RegCont::size_type>(read_nb));

  if (write_reg.size() > std::numeric_limits<int>::max())
  {
    throw std::invalid_argument("Argument \"write_reg\" must not exceed max value of type \"int\"");
  }

  int rc {-1};
  rc = modbus_write_and_read_registers(modbus_connection_,
                                       write_addr, static_cast<int>(write_reg.size()), write_reg.data(),
                                       read_addr, read_nb, read_reg.data());
  ROS_DEBUG_NAMED("LibModbusClient", "modbus_write_and_read_registers: writing from %i %i registers\
                                      and reading from %i %i registers",
                                      write_addr, static_cast<int>(write_reg.size()), read_addr, read_nb);
  if (rc == -1)
  {
    std::string err = "Failed to write and read modbus registers: ";
    err.append(modbus_strerror(errno));
    ROS_ERROR_STREAM_NAMED("LibModbusClient", err);
    throw ModbusExceptionDisconnect(err);
  }

  return read_reg;
}

void LibModbusClient::close()
{
  if (modbus_connection_)
  {
    modbus_close(modbus_connection_);
    modbus_free(modbus_connection_);
    modbus_connection_ = nullptr;
  }
}

} // namespace prbt_hardware_support