implementing the RTU

Peter M. Groen
1 parent 2b90d947
Showing 3 changed files with 104 additions and 18 deletions
src/connectionconfig.h
src/modbusrtu.cpp
src/modbusrtu.h
@@ -7,6 +7,7 @@
 #pragma once
  
 #include <string>
+#include <termios.h>
  
 namespace osdev {
 namespace components {
@@ -29,19 +30,6 @@ public:
         NONE
     };
  
-    enum class E_BAUDRATE
-    {
-        R1200   = 1200,
-        R2400   = 2400,
-        R4800   = 4800,
-        R9600   = 9600,
-        R19200  = 19200,
-        R38400  = 38400,
-        R57600  = 57600,
-        R76800  = 76800,
-        R115200 = 115200
-    };
-
     ConnectionConfig();
  
     // Getters and Setters
@@ -51,8 +39,8 @@ public:
     void                setPortName(const std::string &port_name) { m_portName = port_name; }
     std::string         getPortName() { return m_portName; }
  
-    void                setBaudRate( E_BAUDRATE baud_rate ) { m_baudRate = baud_rate; }
-    E_BAUDRATE          getBaudRate() const { return m_baudRate; }
+    void                setBaudRate( speed_t baud_rate ) { m_baudRate = baud_rate; }
+    speed_t             getBaudRate() const { return m_baudRate; }
  
     void                setParity(E_PARITY parity) { m_parity = parity; }
     E_PARITY            getParity() const { return m_parity; }
@@ -74,8 +62,8 @@ public:
  
 private:
     E_CONNECTIONTYPE    m_conType  = E_CONNECTIONTYPE::UNKNOWN;
-    std::string         m_portName;
-    E_BAUDRATE          m_baudRate = E_BAUDRATE::R9600;
+    std::string         m_portName = "/dev/ttyUSB0";
+    speed_t             m_baudRate = B9600;
     E_PARITY            m_parity   = E_PARITY::NONE;
     int                 m_dataBits = 8;
     int                 m_stopBits = 1;
@@ -4,3 +4,96 @@
  *  This source code is licensed under the MIT license found in the
  *  LICENSE file in the root directory of this source tree.
  */
+
+#include "modbusrtu.h"
+
+#include <stdio.h>
+
+// Linux headers
+#include <fcntl.h>      // Contains file controls like O_RDWR
+#include <errno.h>      // Error integer and strerror() function
+#include <termios.h>    // Contains POSIX terminal control definitions
+#include <unistd.h>     // write(), read(), close()
+
+using namespace osdev::components::modbus;
+
+ModbusRtu::ModbusRtu( const ConnectionConfig &conf )
+    : m_conConfig( conf )
+    , m_socket( -1 )
+{
+}
+
+bool ModbusRtu::Connect()
+{
+    m_socket = open( m_conConfig.getPortName().c_str(), O_RDWR);
+    if(m_socket == -1)
+    {
+        return false;
+    }
+
+    struct termios l_tty;
+
+    // Read in existing settings, and handle any error
+    if( tcgetattr(m_socket, &l_tty) != 0 )
+    {
+        // Replace later on with a logger line.
+        return false;
+    }
+
+    /* Control modes */
+    l_tty.c_cflag &= ~PARENB;                   // Clear parity bit, disabling parity (most common)
+    l_tty.c_cflag &= ~CSTOPB;                   // Clear stop field, only one stop bit used in communication (most common)
+    l_tty.c_cflag &= ~CSIZE;                    // Clear all bits that set the data field
+    l_tty.c_cflag |= CS8;                       // 8 bits per byte (most common)
+    l_tty.c_cflag &= ~CRTSCTS;                  // Disable RTS / CTS hardware flow control (most common)
+    l_tty.c_cflag |= CREAD | CLOCAL;            // Turn on READ & ignore ctrl lines (CLOCAL = 1)
+
+    /* local modes */
+    l_tty.c_lflag &= ~ICANON;                   // ..... Yes..
+    l_tty.c_lflag &= ~ECHO;                     // Disable echo
+    l_tty.c_lflag &= ~ECHOE;                    // Disable Erasure
+    l_tty.c_lflag &= ~ECHONL;                   // Diasble new-line echo
+    l_tty.c_lflag &= ~ISIG;                     // Disable interpretation of INTS, QUIT and SUSP
+    l_tty.c_lflag &= ~(IXON | IXOFF | IXANY );  // Turn off s/w flow control
+
+    /* Ouput modes */
+    l_tty.c_oflag &= ~OPOST;                    // Prevent special interpretation of output bytes (e.g. newline chars)
+    l_tty.c_oflag &= ~ONLCR;                    // Prevent conversion of newline to carriage return/line feed
+
+    // Wait for up to 1 seconds ( 10 deciseconds), returning as soon as any data is received.
+    l_tty.c_cc[VTIME] = 10;
+    l_tty.c_cc[VMIN] = 0;
+
+    // Set the read and write baudrate.
+    cfsetispeed(&l_tty, m_conConfig.getBaudRate());
+    cfsetospeed(&l_tty, m_conConfig.getBaudRate());
+
+    // Save the tty settings.
+    if( tcsetattr(m_socket, TCSANOW, &l_tty) != 0 )
+    {
+        Close();
+        return false;
+    }
+
+    return true;
+}
+
+bool ModbusRtu::Close()
+{
+    if( close(m_socket) != 0 )
+    {
+        return false;
+    }
+    return true;
+}
+
+int ModbusRtu::modbusSend(uint8_t *to_send, size_t length)
+{
+    return write(m_socket, to_send, length);
+
+}
+
+int ModbusRtu::modbusReceive(uint8_t *buffer)
+{
+    return read(m_socket, buffer, sizeof(*buffer));
+}
@@ -6,6 +6,7 @@
  */
  
 #include "modbusbase.h"
+#include "connectionconfig.h"
  
 namespace osdev {
 namespace components {
@@ -14,6 +15,9 @@ namespace modbus {
 class ModbusRtu : public ModbusBase
 {
 public:
+    ModbusRtu( const ConnectionConfig &conf );
+    virtual ~ModbusRtu() {}
+
     virtual bool Connect() override;
     virtual bool Close() override;
  
@@ -33,7 +37,8 @@ public:
     virtual int modbusReceive(uint8_t *buffer) override;
  
 private:
-
+    ConnectionConfig    m_conConfig;
+    int                 m_socket;
 };
  
 }   /* End namespace modbus */