add TCP comm mode for Novelec protocol

conanfile.py

@@ -2,7 +2,7 @@ from conan import ConanFile
 
 class electrometersRecipe(ConanFile):
     name = "electrometers"
-    version = "2.7.1"
+    version = "2.8.0"
     package_type = "library"
     user = "soleil"
     python_requires = "base/[>=1.0]@soleil/stable"

include/N_PhotoConducteur.h

@@ -36,7 +36,7 @@ public:
 	*  \brief Initialization.
 	*/
 //	N_PhotoConducteur (std::string& comLink_device_name, short channel_address, short electroType);
-	N_PhotoConducteur (std::string& comLink_device_name, short channel_address);
+	N_PhotoConducteur (std::string& comLink_device_name, short channel_address, std::string comProtocol);
 
 	/**
 	*  \brief Release resources.

include/N_PhotoVoltaique.h

@@ -36,7 +36,7 @@ public:
 	*  \brief Initialization.
 	*/
 //	N_PhotoVoltaique (std::string comLink_device_name, short channel_address, short electroType);
-	N_PhotoVoltaique (std::string comLink_device_name, short channel_address);
+	N_PhotoVoltaique (std::string comLink_device_name, short channel_address, std::string comProtocol);
 
 	/**
 	*  \brief Release resources.

include/NovelecProtocol.h

@@ -17,6 +17,7 @@
 #include "ElectrometerProtocol.h"
 #include "ElectrometerException.h"
 #include "TangoSerialLink.h"
+#include "TangoEthernetLink.h"
 
 /**
  *  \addtogroup Standard Commands Protocol
@@ -38,7 +39,7 @@ public:
 	*  \brief Initialization.
 	*/
 	//NovelecProtocol (std::string& communication_device_name, unsigned short channel_address, unsigned short electroTypeNumber);
-	NovelecProtocol (std::string& communication_device_name, unsigned short channel_address);
+	NovelecProtocol (std::string& communication_device_name, unsigned short channel_address, std::string comProtocol);
 
 	/**
 	*  \brief Release resources.
@@ -129,11 +130,15 @@ private :
 	void is_allowed();
 
 	CommunicationLink* _communication_link;
+	//communication protocol ETHERNET/SERIAL
+	std::string _comProtocol;
 
 	//- if true, parameters cannot be changed !
 	bool	_is_measure_mode_on;
 	//- if true, explicite response mode is enabled
 	bool	_is_explicite_resp_enabled;
+  //- the specific new line character
+  string END_OF_LINE ;
 
 };
 

include/Novelec_MCCE2.h

@@ -36,7 +36,7 @@ public:
 	*  \brief Initialization.
 	*/
 //	Novelec_MCCE2 (std::string& comLink_device_name, unsigned short channel_address, unsigned short electroType);
-	Novelec_MCCE2 (std::string& comLink_device_name, unsigned short channel_address);
+	Novelec_MCCE2 (std::string& comLink_device_name, unsigned short channel_address, std::string comProtocol);
 
 	/**
 	*  \brief Release resources.
@@ -100,6 +100,8 @@ protected :
 	*	\brief Checks the new range value
 	*/
 	short check_range_value(const std::string& rgToCheck, const std::vector<std::string>	 electroRangeList);
+private:
+	std::string _comProtocol;
 
 };
 

include/TangoEthernetLink.h

+// ============================================================================
+//
+// = CONTEXT
+//    TANGO Project - Keithley Electrometer Support Library
+//
+// = FILENAME
+//    TangoEthernetLink.h
+//
+// = AUTHOR
+//    X. Elattaoui
+//
+// ============================================================================
+
+#ifndef _TANGO_ETHERNET_LINK_H_
+#define _TANGO_ETHERNET_LINK_H_
+
+// ============================================================================
+// DEPENDENCIES
+// ============================================================================
+#include <tango.h>
+#include "CommunicationLink.h"
+
+/**
+ *  \addtogroup Communication Management
+ *  @{
+ */
+
+/**
+ *  \brief This class manage the ETHERNET communication bus
+ *
+ *  \author
+ *  \date
+ */
+
+class TangoEthernetLink : public CommunicationLink
+{
+
+public :
+ 	/**
+	* \brief Initialization.
+	*/
+	TangoEthernetLink (std::string& serial_device_name);
+
+	/**
+	* \brief Release resources.
+	*/
+	~TangoEthernetLink ();
+
+	/**
+	*  \brief Send command (data) as string to hardware.
+	*
+	*  \throws Tango::DevFailed
+	*/
+	void write(std::string cmd)	 throw (Tango::DevFailed);
+
+	std::string read(void) throw (Tango::DevFailed);
+
+	/**
+	*  \brief Performs a write read operation as string. (read nb char)
+	*
+	*  \throws Tango::DevFailed
+	*/
+	std::string write_read(std::string cmd, size_t nbChar)  throw (Tango::DevFailed);
+
+private :
+
+  /**
+	* Creates a proxy on the specified Serial Device.
+	*/
+	void check_proxy(void) throw (Tango::DevFailed);
+
+	Tango::DeviceProxy* _ethernet_proxy;
+
+	bool _is_ethernet_proxy_ok;
+
+};
+
+/** @} */	//- end addtogroup
+
+#endif // _TANGO_ETHERNET_LINK_H_

include/TangoSerialLink.h

@@ -4,7 +4,7 @@
 //    TANGO Project - Keithley Electrometer Support Library
 //
 // = FILENAME
-//    TangoSerialLink.h
+//    TangoSerialLink.h.h
 //
 // = AUTHOR
 //    X. Elattaoui
@@ -79,12 +79,11 @@ private :
   /**
 	* Creates a proxy on the specified Serial Device.
 	*/
-	void create_serial_proxy(void) throw (Tango::DevFailed);
+	void check_proxy(void) throw (Tango::DevFailed);
 
-	//Tango::DeviceProxyHelper* _serial_proxy;
 	Tango::DeviceProxy* _serial_proxy;
 
-	bool _is_serial_proxy_created;
+	bool _is_serial_proxy_ok;
 
 };
 

pom.xml

@@ -8,7 +8,7 @@
    </parent>
    <groupId>fr.soleil.lib</groupId>
    <artifactId>Electrometers-${aol}-${library}-${mode}</artifactId>
-   <version>2.7.1</version>
+   <version>2.8.0</version>
    <packaging>nar</packaging>
    <name>Electrometers library</name>
    <description>Electrometers library</description>

src/N_PhotoConducteur.cpp

@@ -31,8 +31,8 @@ static const std::vector<std::string> NType5_rangeValue {"1000","300","100","30"
 // ============================================================================
 // N_PhotoConducteur::N_PhotoConducteur
 // ============================================================================
-N_PhotoConducteur::N_PhotoConducteur (std::string& comLink_device_name, short address)
-:	Novelec_MCCE2(comLink_device_name, address)
+N_PhotoConducteur::N_PhotoConducteur (std::string& comLink_device_name, short address, std::string comProtocol)
+:	Novelec_MCCE2(comLink_device_name, address, comProtocol)
 {
 	//std::cout << "N_PhotoConducteur::N_PhotoConducteur <-" << std::endl;
 
@@ -46,7 +46,7 @@ N_PhotoConducteur::N_PhotoConducteur (std::string& comLink_device_name, short ad
 // ============================================================================
 N_PhotoConducteur::~N_PhotoConducteur (void)
 {
-	//std::cout << "N_PhotoConducteur::~N_PhotoConducteur <-" << std::endl;
+	std::cout << "N_PhotoConducteur::~N_PhotoConducteur <-" << std::endl;
 
 	//std::cout << "N_PhotoConducteur::~N_PhotoConducteur ->" << std::endl;
 }

src/N_PhotoVoltaique.cpp

@@ -32,10 +32,10 @@ static const std::vector<std::string> NType3_rangeValue {"1E-08AcC","3E-08AcC","
 // ============================================================================
 // N_PhotoVoltaique::N_PhotoVoltaique
 // ============================================================================
-N_PhotoVoltaique::N_PhotoVoltaique (std::string comLink_device_name, short address)
-:	Novelec_MCCE2(comLink_device_name, address)
+N_PhotoVoltaique::N_PhotoVoltaique (std::string comLink_device_name, short address, std::string comProtocol)
+:	Novelec_MCCE2(comLink_device_name, address, comProtocol)
 {
-	//std::cout << "N_PhotoVoltaique::N_PhotoVoltaique <-" << std::endl;
+	std::cout << "N_PhotoVoltaique::N_PhotoVoltaique <-" << std::endl;
 
 	//std::cout << "N_PhotoVoltaique::N_PhotoVoltaique ->" << std::endl;
 }

src/NovelecProtocol.cpp

@@ -40,8 +40,7 @@ static const short  RESPONSE_LGTH_CMD_NUM       = 17;
 static const short  CLEAR_ERRORS_CMD_NUM        = 18;
 static const long   PILOTAGE_AND_PROG_RESP_LGTH = 10;
 static const long   READ_DATA_RESP_LGTH         = 24;
-//- the specific new line character
-static const char END_OF_LINE[] = "\r\n";
+
 //- modes allowed
 static const std::string mode_str[] = {"ERR : UNKNOWN MODE","ZERO V/F","OFFSET","LEAKAGE","TEST","MEASURE"};
 static const std::string range_str[5][8] = {
@@ -54,36 +53,21 @@ static const std::string range_str[5][8] = {
 static const std::string frequency_str[]= {"3 Hz","10 Hz","100 Hz","1000 Hz"};
 static const std::string gain_str[]   = {"1","10","100"};
 
-/*
-// ============================================================================
-// NovelecProtocol::NovelecProtocol
-// ============================================================================
-NovelecProtocol::NovelecProtocol (std::string& serial_device_name, unsigned short devAddress, unsigned short novelecType)
-  : ElectrometerProtocol(),
-    _devAdd(devAddress),
-    _novType(novelecType),
-    _rangeParameterNum(0),
-    _communication_link(0),
-    _is_measure_mode_on(false),
-    _is_explicite_resp_enabled(false)
-{
-  _commDevName = serial_device_name;
-  _function = "Not updated";
-}
-*/
+
 // ============================================================================
 // NovelecProtocol::NovelecProtocol
 // ============================================================================
-NovelecProtocol::NovelecProtocol (std::string& serial_device_name, unsigned short devAddress)
+NovelecProtocol::NovelecProtocol (std::string& communication_device_name, unsigned short devAddress, std::string comProtocol)
   : ElectrometerProtocol(),
     _devAdd(devAddress),
     _novType(0),
     _rangeParameterNum(0),
     _communication_link(0),
+    _comProtocol(comProtocol),
     _is_measure_mode_on(false),
     _is_explicite_resp_enabled(false)
 {
-  _commDevName = serial_device_name;
+  _commDevName = communication_device_name;
   _function = "Not updated";
 }
 
@@ -108,8 +92,17 @@ bool NovelecProtocol::build_communicationLink()
 {
   if (_commDevName.empty())
     return false;
-
+  std::cout<<"NovelecProtocol::build_communicationLink "<<_comProtocol<<std::endl;
+  if (_comProtocol=="SERIAL")
+  {
     _communication_link = new TangoSerialLink(_commDevName);
+    END_OF_LINE = "\r\n";
+  }
+  else if (_comProtocol=="ETHERNET")
+  {
+    _communication_link = new TangoEthernetLink(_commDevName);
+    END_OF_LINE ="";
+  }
 
   if (!_communication_link)
     return false;
@@ -804,8 +797,6 @@ std::string NovelecProtocol::check_and_extract_data (std::string response, short
         pos = data.find(" ");
       }
 
-      /*data.erase(data.find_first_of(" "),1);
-      data.erase(data.find_last_of(" ")); */
     }
     else
       throw electrometer::ElectrometerException("SYNCHRONISATION_LOST",

src/Novelec_MCCE2.cpp

@@ -39,16 +39,17 @@
 // ============================================================================
 // Novelec_MCCE2::Novelec_MCCE2
 // ============================================================================
-Novelec_MCCE2::Novelec_MCCE2 (std::string& comLink_device_name, unsigned short address)
+Novelec_MCCE2::Novelec_MCCE2 (std::string& comLink_device_name, unsigned short address, std::string comProtocol)
 :	AbstractElectrometerClass(comLink_device_name),
 	_rangeLimit(0),
   _address(address),
 	_MCCE2electroTypeNumber(0),
-	_MCCE2electroTypeStr("Unknown type")
+	_MCCE2electroTypeStr("Unknown type"),
+	_comProtocol(comProtocol)
 {
-	std::cout << "\t\tNovelec_MCCE2::Novelec_MCCE2 <-" << std::endl;
+	std::cout << "\t\tNovelec_MCCE2::Novelec_MCCE2 <-" <<comProtocol<< std::endl;
+
 
-	std::cout << "\t\tNovelec_MCCE2::Novelec_MCCE2 ->" << std::endl;
 }
 
 // ============================================================================
@@ -58,7 +59,6 @@ Novelec_MCCE2::~Novelec_MCCE2 (void)
 {
 	//std::cout << "Novelec_MCCE2::~Novelec_MCCE2 <-" << std::endl;
 
-	//std::cout << "Novelec_MCCE2::~Novelec_MCCE2 ->" << std::endl;
 }
 
 // ============================================================================
@@ -71,7 +71,7 @@ bool Novelec_MCCE2::init_protocol (void)
   try
   {
 	  //- build the keithley Electrometer protocol obj
-	_electrometerProtocol = new NovelecProtocol(_device_proxy_name, _address);
+	  _electrometerProtocol = new NovelecProtocol(_device_proxy_name, _address,_comProtocol);
 
     if(_electrometerProtocol)
       success = _electrometerProtocol->build_communicationLink();

src/TangoEthernetLink.cpp

+// ============================================================================
+//
+// = CONTEXT
+//    TANGO Project - Keithley Electrometer Support Library
+//
+// = FILENAME
+//    TangoEthernetLink.cpp
+//
+// = AUTHOR
+//    X. Elattaoui
+//
+// ============================================================================
+
+// ============================================================================
+// DEPENDENCIES
+// ============================================================================
+#include <string>
+#include <iostream>
+#include "TangoEthernetLink.h"
+
+
+
+// ============================================================================
+// TangoEthernetLink::TangoEthernetLink
+// ============================================================================
+TangoEthernetLink::TangoEthernetLink (std::string& serial_device_name)
+:	CommunicationLink(serial_device_name),
+	_ethernet_proxy (0),
+	_is_ethernet_proxy_ok (false)
+{
+}
+
+// ============================================================================
+// TangoEthernetLink::~TangoEthernetLink
+// ============================================================================
+TangoEthernetLink::~TangoEthernetLink (void)
+{
+
+	if(_ethernet_proxy)
+	{
+		delete _ethernet_proxy;
+		_ethernet_proxy = 0;
+		_is_ethernet_proxy_ok = false;
+	}
+
+}
+
+
+// ============================================================================
+// TangoEthernetLink::create_ethernet_proxy
+// ============================================================================
+void TangoEthernetLink::check_proxy (void)  throw (Tango::DevFailed)
+{
+  std::string description("");
+
+	try
+	{
+		//- try
+		this->_ethernet_proxy = new Tango::DeviceProxy(_communication_Device_name.c_str());
+		_ethernet_proxy->ping();
+		_is_ethernet_proxy_ok = true;
+	}
+	catch(Tango::DevFailed& df )
+	{
+		if( this->_ethernet_proxy )
+		{
+			delete this->_ethernet_proxy;
+			this->_ethernet_proxy = 0;
+		}
+		_is_ethernet_proxy_ok = false;
+		description = "Unable to create proxy on : " + _communication_Device_name;
+		Tango::Except::re_throw_exception (df,
+										(const char*)"ALLOCATION_ERROR",
+										description.c_str(),
+										(const char*)"TangoEthernetLink::create_ethernet_proxy");
+
+	}
+	catch(...)
+	{
+		if( this->_ethernet_proxy )
+		{
+			delete this->_ethernet_proxy;
+			this->_ethernet_proxy = 0;
+		}
+		_is_ethernet_proxy_ok = false;
+		description = "Unable to create proxy on : " + _communication_Device_name + "\nmemory allocation failed.";
+		Tango::Except::throw_exception (
+										(const char*)"ALLOCATION_ERROR",
+										description.c_str(),
+										(const char*)"TangoEthernetLink::write");
+	}
+}
+
+// ============================================================================
+// TangoEthernetLink::write
+// ============================================================================
+void TangoEthernetLink::write (std::string command_to_send)  throw (Tango::DevFailed)
+{
+  std::string description("");
+
+	check_proxy();
+	if (!_is_ethernet_proxy_ok)
+		return;
+
+	Tango::DeviceData dd_in;
+	Tango::DevString argin = 0;
+
+	try
+	{
+		argin = new char [command_to_send.size() + 1];
+		strcpy(argin, command_to_send.c_str());
+	}
+	catch(Tango::DevFailed& df )
+	{
+		if( argin )
+		{
+			delete [] argin;
+			argin = 0;
+		}
+		description = "Unable to write command : " + command_to_send +  + "\nmemory allocation failed.";
+		Tango::Except::re_throw_exception (df,
+										(const char*)"ALLOCATION_ERROR",
+										description.c_str(),
+										(const char*)"TangoEthernetLink::write");
+	}
+	catch(...)
+	{
+		description = "Unable to write command : " + command_to_send + "\nmemory allocation failed.";
+		Tango::Except::throw_exception (
+										(const char*)"ALLOCATION_ERROR",
+										description.c_str(),
+										(const char*)"TangoEthernetLink::write");
+	}
+
+	try
+	{
+		//- try
+		dd_in << argin;
+		_ethernet_proxy->command_inout("Write", dd_in);
+		if( argin )
+		{
+			delete [] argin;
+			argin = 0;
+		}
+		//std::cout << "TangoEthernetLink::write -> argin = *\"" << argin << "\"*" << std::endl;
+	}
+	catch(Tango::DevFailed& df )
+	{
+		if( argin )
+		{
+			delete [] argin;
+			argin = 0;
+		}
+		description = "Unable to write command : " + command_to_send;
+		Tango::Except::re_throw_exception (df,
+										(const char*)"COMMUNICATION_ERROR",
+										description.c_str(),
+										(const char*)"TangoEthernetLink::write");
+
+	}
+	catch(...)
+	{
+		if( argin )
+		{
+			delete [] argin;
+			argin = 0;
+		}
+		description = "Unable to write command : " + command_to_send;
+		Tango::Except::throw_exception (
+										(const char*)"COMMUNICATION_ERROR",
+										description.c_str(),
+										(const char*)"TangoEthernetLink::write");
+	}
+}
+
+
+// ============================================================================
+// TangoEthernetLink::read
+// ============================================================================
+std::string TangoEthernetLink::read (void) throw (Tango::DevFailed)
+{
+
+	check_proxy();
+	if(!_is_ethernet_proxy_ok)
+		return "";
+
+	Tango::DeviceData dd_out;
+	std::string response("");
+
+	try
+	{
+
+		dd_out = _ethernet_proxy->command_inout("Read");
+		dd_out >> response;
+	}
+	catch(Tango::DevFailed& df )
+	{
+		Tango::Except::re_throw_exception (df,
+										(const char*)"COMMUNICATION_ERROR",
+										(const char*)"Unable to perform a read operation",
+										(const char*)"TangoEthernetLink::read");
+	}
+	catch(...)
+	{
+		Tango::Except::throw_exception (
+										(const char*)"COMMUNICATION_ERROR",
+										(const char*)"Unable to perform a read operation",
+										(const char*)"TangoEthernetLink::read");
+	}
+
+	return response ;
+}
+
+// ============================================================================
+// TangoEthernetLink::write_read : read N char
+// ============================================================================
+std::string TangoEthernetLink::write_read (std::string command_to_send, size_t nbChar) throw (Tango::DevFailed)
+{
+	std::string resp;
+
+	check_proxy();
+	if(!_is_ethernet_proxy_ok)
+		return "";
+
+	Tango::DeviceData dd_in;
+	Tango::DevString argin = 0;
+
+	Tango::DeviceData dd_out;
+	std::string response("");
+
+	try
+	{
+		argin = new char [command_to_send.size() + 1];
+		strcpy(argin, command_to_send.c_str());
+		dd_in << argin;
+		dd_out = _ethernet_proxy->command_inout("WriteRead", dd_in);
+		dd_out >> response;
+	}
+	catch(Tango::DevFailed& df )
+	{
+		Tango::Except::re_throw_exception (df,
+										(const char*)"COMMUNICATION_ERROR",
+										(const char*)"Unable to perform a read operation",
+										(const char*)"TangoEthernetLink::read");
+	}
+	catch(...)
+	{
+		Tango::Except::throw_exception (
+										(const char*)"COMMUNICATION_ERROR",
+										(const char*)"Unable to perform a read operation",
+										(const char*)"TangoEthernetLink::read");
+	}
+
+	return response ;
+
+
+}
+

src/TangoSerialLink.cpp

@@ -28,11 +28,10 @@ static const long MODE_LINE = 2;
 TangoSerialLink::TangoSerialLink (std::string& serial_device_name)
 :	CommunicationLink(serial_device_name),
 	_serial_proxy (0),
-	_is_serial_proxy_created (false)
+	_is_serial_proxy_ok (false)
 {
-//	//std::cout << "TangoSerialLink::TangoSerialLink <-" << std::endl;
+	//std::cout << "TangoSerialLink::TangoSerialLink <-" << std::endl;
 
-//	//std::cout << "TangoSerialLink::TangoSerialLink ->" << std::endl;
 }
 
 // ============================================================================
@@ -46,7 +45,7 @@ TangoSerialLink::~TangoSerialLink (void)
 	{
 		delete _serial_proxy;
 		_serial_proxy = 0;
-		_is_serial_proxy_created = false;
+		_is_serial_proxy_ok = false;
 	}
 
 	std::cout << "TangoSerialLink::~TangoSerialLink ->" << std::endl;
@@ -56,16 +55,19 @@ TangoSerialLink::~TangoSerialLink (void)
 // ============================================================================
 // TangoSerialLink::create_serial_proxy
 // ============================================================================
-void TangoSerialLink::create_serial_proxy (void)  throw (Tango::DevFailed)
+void TangoSerialLink::check_proxy (void)  throw (Tango::DevFailed)
 {
   std::string description("");
 
 	try
 	{
-		//- try
-		this->_serial_proxy = new Tango::DeviceProxy(_communication_Device_name.c_str());
-		//(*_serial_proxy)->ping();
-		_is_serial_proxy_created = true;
+		if (_serial_proxy==0)
+		{
+			_serial_proxy = new Tango::DeviceProxy(_communication_Device_name.c_str());
+		}
+
+		_serial_proxy->ping();
+		_is_serial_proxy_ok = true;
 	}
 	catch(Tango::DevFailed& df )
 	{
@@ -74,13 +76,12 @@ void TangoSerialLink::create_serial_proxy (void)  throw (Tango::DevFailed)
 			delete this->_serial_proxy;
 			this->_serial_proxy = 0;
 		}
-		_is_serial_proxy_created = false;
-		description = "Unable to create proxy on : " + _communication_Device_name;
+		_is_serial_proxy_ok = false;
+		description = "Cannot connect to : " + _communication_Device_name;
 		Tango::Except::re_throw_exception (df,
 										(const char*)"ALLOCATION_ERROR",
 										description.c_str(),
-										(const char*)"TangoSerialLink::create_serial_proxy");
-
+										(const char*)"TangoSerialLink::check_proxy");
 	}
 	catch(...)
 	{
@@ -89,12 +90,12 @@ void TangoSerialLink::create_serial_proxy (void)  throw (Tango::DevFailed)
 			delete this->_serial_proxy;
 			this->_serial_proxy = 0;
 		}
-		_is_serial_proxy_created = false;
+		_is_serial_proxy_ok = false;
 		description = "Unable to create proxy on : " + _communication_Device_name + "\nmemory allocation failed.";
 		Tango::Except::throw_exception (
 										(const char*)"ALLOCATION_ERROR",
 										description.c_str(),
-										(const char*)"TangoSerialLink::write");
+										(const char*)"TangoSerialLink::check_proxy");
 	}
 }
 
@@ -105,8 +106,9 @@ void TangoSerialLink::write (std::string command_to_send)  throw (Tango::DevFail
 {
   std::string description("");
 
+  check_proxy();
 	if(!_serial_proxy)
-		create_serial_proxy();
+		return ;
 	Tango::DeviceData dd_in;
 	Tango::DevString argin = 0;
 
@@ -185,8 +187,9 @@ void TangoSerialLink::write (std::string command_to_send)  throw (Tango::DevFail
 std::string TangoSerialLink::read (void) throw (Tango::DevFailed)
 {
 
+  check_proxy();
 	if(!_serial_proxy)
-		create_serial_proxy();
+		return "";
 	Tango::DeviceData dd_out;
 	std::string response("");
 
@@ -220,8 +223,10 @@ std::string TangoSerialLink::read (void) throw (Tango::DevFailed)
 std::string TangoSerialLink::read (long nbCharToRead) throw (Tango::DevFailed)
 {
 
+  check_proxy();
 	if(!_serial_proxy)
-		create_serial_proxy();
+		return "";
+
 	Tango::DeviceData dd_in;
 	Tango::DeviceData dd_out;
 	std::string response("");
@@ -253,8 +258,9 @@ std::string TangoSerialLink::write_read (std::string command_to_send, size_t nbC
 	Tango::DeviceData dd_in;
 	Tango::DeviceData dd_out;
 
+  check_proxy();
 	if(!_serial_proxy)
-		create_serial_proxy();
+		return "";
 
 	long flush_in_out = 2;
 	dd_in << flush_in_out;