diff --git a/Common/engine_interface_base.h b/Common/engine_interface_base.h
index 846b608..0435ab8 100644
--- a/Common/engine_interface_base.h
+++ b/Common/engine_interface_base.h
@@ -44,9 +44,18 @@ public:
 	//! Get the (interpolated) magnetic field at \p pos. \sa SetInterpolationType
 	virtual double* GetHField(const unsigned int* pos, double* out) const {UNUSED(pos);return out;}
 
+	//! Calculate the electric field integral along a given line
+	virtual double CalcVoltageIntegral(const unsigned int* start, const unsigned int* stop) const {UNUSED(start);UNUSED(stop);return 0.0;}
+
 	//! Convert the interpolation type into a string.
 	static std::string GetInterpolationNameByType(InterpolationType mode);
 
+	//! Get the current simulation time
+	virtual double GetTime(bool dualTime=false) const {UNUSED(dualTime);return 0.0;}
+
+	//! Get the current number of timesteps
+	virtual unsigned int GetNumberOfTimesteps() const {return 0;}
+
 protected:
     Engine_Interface_Base();
 
diff --git a/FDTD/engine_interface_fdtd.cpp b/FDTD/engine_interface_fdtd.cpp
index e138e1f..19169e0 100644
--- a/FDTD/engine_interface_fdtd.cpp
+++ b/FDTD/engine_interface_fdtd.cpp
@@ -161,3 +161,24 @@ double* Engine_Interface_FDTD::GetHField(const unsigned int* pos, double* out) c
 
 	return out;
 }
+
+double Engine_Interface_FDTD::CalcVoltageIntegral(const unsigned int* start, const unsigned int* stop) const
+{
+	double result=0;
+	for (int n=0;n<3;++n)
+	{
+		if (start[n]<stop[n])
+		{
+			unsigned int pos[3]={start[0],start[1],start[2]};
+			for (;pos[n]<stop[n];++pos[n])
+				result += m_Eng->GetVolt(n,pos[0],pos[1],pos[2]);
+		}
+		else
+		{
+			unsigned int pos[3]={stop[0],stop[1],stop[2]};
+			for (;pos[n]<start[n];++pos[n])
+				result -= m_Eng->GetVolt(n,pos[0],pos[1],pos[2]);
+		}
+	}
+	return result;
+}
diff --git a/FDTD/engine_interface_fdtd.h b/FDTD/engine_interface_fdtd.h
index c4e0ad1..f5118ca 100644
--- a/FDTD/engine_interface_fdtd.h
+++ b/FDTD/engine_interface_fdtd.h
@@ -44,6 +44,11 @@ public:
 	virtual double* GetEField(const unsigned int* pos, double* out) const;
 	virtual double* GetHField(const unsigned int* pos, double* out) const;
 
+	virtual double CalcVoltageIntegral(const unsigned int* start, const unsigned int* stop) const;
+
+	virtual double GetTime(bool dualTime=false) const {return ((double)m_Eng->GetNumberOfTimesteps() + (double)dualTime*0.5)*m_Op->GetTimestep();};
+	virtual unsigned int GetNumberOfTimesteps() const {return m_Eng->GetNumberOfTimesteps();}
+
 protected:
 	Operator* m_Op;
 	Engine* m_Eng;
diff --git a/FDTD/process_efield.cpp b/FDTD/process_efield.cpp
index b1c189c..dc91a54 100644
--- a/FDTD/process_efield.cpp
+++ b/FDTD/process_efield.cpp
@@ -19,8 +19,9 @@
 #include "time.h"
 #include "process_efield.h"
 
-ProcessEField::ProcessEField(Operator* op, Engine* eng) : Processing(op, eng)
+ProcessEField::ProcessEField(Operator* op, Engine* eng) : Processing(op)
 {
+	Eng = eng;
 }
 
 ProcessEField::~ProcessEField()
diff --git a/FDTD/process_efield.h b/FDTD/process_efield.h
index 6189a49..9f01315 100644
--- a/FDTD/process_efield.h
+++ b/FDTD/process_efield.h
@@ -37,6 +37,7 @@ public:
 	virtual int Process();
 
 protected:
+	Engine* Eng;
 	vector<double_complex> FD_Values[3];
 };
 
diff --git a/FDTD/processcurrent.cpp b/FDTD/processcurrent.cpp
index 6663acc..864b6a1 100644
--- a/FDTD/processcurrent.cpp
+++ b/FDTD/processcurrent.cpp
@@ -17,9 +17,10 @@
 
 #include "tools/global.h"
 #include "processcurrent.h"
+#include "engine_interface_fdtd.h"
 #include <iomanip>
 
-ProcessCurrent::ProcessCurrent(Operator* op, Engine* eng) : ProcessIntegral(op, eng)
+ProcessCurrent::ProcessCurrent(Operator* op) : ProcessIntegral(op)
 {
 	m_TimeShift = op->GetTimestep()/2.0;
 	m_dualMesh = true;
@@ -33,96 +34,103 @@ double ProcessCurrent::CalcIntegral()
 {
 	FDTD_FLOAT current=0;
 
-	int Dump_Dim = 0;
-	int NormDir = 0;
+	Engine_Interface_FDTD* EI_FDTD = dynamic_cast<Engine_Interface_FDTD*>(m_Eng_Interface);
 
-	for (int n=0;n<3;++n)
+	if (EI_FDTD)
 	{
-		if (start[n]>stop[n])
+		const Engine* Eng = EI_FDTD->GetFDTDEngine();
+
+		int Dump_Dim = 0;
+		int NormDir = 0;
+
+		for (int n=0;n<3;++n)
 		{
-			unsigned int help=start[n];
-			start[n]=stop[n];
-			stop[n]=help;
-			bool b_help=m_start_inside[n];
-			m_start_inside[n] = m_stop_inside[n];
-			m_stop_inside[n] = b_help;
+			if (start[n]>stop[n])
+			{
+				unsigned int help=start[n];
+				start[n]=stop[n];
+				stop[n]=help;
+				bool b_help=m_start_inside[n];
+				m_start_inside[n] = m_stop_inside[n];
+				m_stop_inside[n] = b_help;
+			}
+			if (m_stop_inside[n]==false) // integrate up to the wall, Operator::SnapToMesh would give numLines[n]-2
+				stop[n]=Op->GetNumberOfLines(n)-1;
+
+			if (stop[n]>start[n])
+				++Dump_Dim;
+			if (stop[n] == start[n])
+				NormDir = n;
 		}
-		if (m_stop_inside[n]==false) // integrate up to the wall, Operator::SnapToMesh would give numLines[n]-2
-			stop[n]=Op->GetNumberOfLines(n)-1;
 
-		if (stop[n]>start[n])
-			++Dump_Dim;
-		if (stop[n] == start[n])
-			NormDir = n;
-	}
+		if (Dump_Dim!=2)
+		{
+			cerr << "ProcessCurrent::Process(): Warning Current Integration Box \"" << m_filename << "\" is not a surface (found dimension: " << Dump_Dim << ") --> i = 0" << endl;
+			current = 0;
+			return 0.0;
+		}
 
-	if (Dump_Dim!=2)
-	{
-		cerr << "ProcessCurrent::Process(): Warning Current Integration Box \"" << m_filename << "\" is not a surface (found dimension: " << Dump_Dim << ") --> i = 0" << endl;
-		current = 0;
-		return 0.0;
-	}
-
-	switch (NormDir)
-	{
-	case 0:
-		//y-current
-		if (m_stop_inside[0] && m_start_inside[2])
-			for (unsigned int i=start[1]+1;i<=stop[1];++i)
-				current+=Eng->GetCurr(1,stop[0],i,start[2]);
-		//z-current
-		if (m_stop_inside[0] && m_stop_inside[1])
-			for (unsigned int i=start[2]+1;i<=stop[2];++i)
-				current+=Eng->GetCurr(2,stop[0],stop[1],i);
-		//y-current
-		if (m_start_inside[0] && m_stop_inside[2])
-			for (unsigned int i=start[1]+1;i<=stop[1];++i)
-				current-=Eng->GetCurr(1,start[0],i,stop[2]);
-		//z-current
-		if (m_start_inside[0] && m_start_inside[1])
-			for (unsigned int i=start[2]+1;i<=stop[2];++i)
-				current-=Eng->GetCurr(2,start[0],start[1],i);
-		break;
-	case 1:
-		//z-current
-		if (m_start_inside[0] && m_start_inside[1])
-			for (unsigned int i=start[2]+1;i<=stop[2];++i)
-				current+=Eng->GetCurr(2,start[0],start[1],i);
-		//x-current
-		if (m_stop_inside[1] && m_stop_inside[2])
-			for (unsigned int i=start[0]+1;i<=stop[0];++i)
-				current+=Eng->GetCurr(0,i,stop[1],stop[2]);
-		//z-current
-		if (m_stop_inside[0] && m_stop_inside[1])
-			for (unsigned int i=start[2]+1;i<=stop[2];++i)
-				current-=Eng->GetCurr(2,stop[0],stop[1],i);
-		//x-current
-		if (m_start_inside[1] && m_start_inside[2])
-			for (unsigned int i=start[0]+1;i<=stop[0];++i)
-				current-=Eng->GetCurr(0,i,start[1],start[2]);
-		break;
-	case 2:
-		//x-current
-		if (m_start_inside[1] && m_start_inside[2])
-			for (unsigned int i=start[0]+1;i<=stop[0];++i)
-				current+=Eng->GetCurr(0,i,start[1],start[2]);
-		//y-current
-		if (m_stop_inside[0] && m_start_inside[2])
-			for (unsigned int i=start[1]+1;i<=stop[1];++i)
-				current+=Eng->GetCurr(1,stop[0],i,start[2]);
-		//x-current
-		if (m_stop_inside[1] && m_stop_inside[2])
-			for (unsigned int i=start[0]+1;i<=stop[0];++i)
-				current-=Eng->GetCurr(0,i,stop[1],stop[2]);
-		//y-current
-		if (m_start_inside[0] && m_stop_inside[2])
-			for (unsigned int i=start[1]+1;i<=stop[1];++i)
-				current-=Eng->GetCurr(1,start[0],i,stop[2]);
-		break;
-	default:
-		//this cannot happen...
-		return 0.0;
-		break;
+		switch (NormDir)
+		{
+		case 0:
+			//y-current
+			if (m_stop_inside[0] && m_start_inside[2])
+				for (unsigned int i=start[1]+1;i<=stop[1];++i)
+					current+=Eng->GetCurr(1,stop[0],i,start[2]);
+			//z-current
+			if (m_stop_inside[0] && m_stop_inside[1])
+				for (unsigned int i=start[2]+1;i<=stop[2];++i)
+					current+=Eng->GetCurr(2,stop[0],stop[1],i);
+			//y-current
+			if (m_start_inside[0] && m_stop_inside[2])
+				for (unsigned int i=start[1]+1;i<=stop[1];++i)
+					current-=Eng->GetCurr(1,start[0],i,stop[2]);
+			//z-current
+			if (m_start_inside[0] && m_start_inside[1])
+				for (unsigned int i=start[2]+1;i<=stop[2];++i)
+					current-=Eng->GetCurr(2,start[0],start[1],i);
+			break;
+		case 1:
+			//z-current
+			if (m_start_inside[0] && m_start_inside[1])
+				for (unsigned int i=start[2]+1;i<=stop[2];++i)
+					current+=Eng->GetCurr(2,start[0],start[1],i);
+			//x-current
+			if (m_stop_inside[1] && m_stop_inside[2])
+				for (unsigned int i=start[0]+1;i<=stop[0];++i)
+					current+=Eng->GetCurr(0,i,stop[1],stop[2]);
+			//z-current
+			if (m_stop_inside[0] && m_stop_inside[1])
+				for (unsigned int i=start[2]+1;i<=stop[2];++i)
+					current-=Eng->GetCurr(2,stop[0],stop[1],i);
+			//x-current
+			if (m_start_inside[1] && m_start_inside[2])
+				for (unsigned int i=start[0]+1;i<=stop[0];++i)
+					current-=Eng->GetCurr(0,i,start[1],start[2]);
+			break;
+		case 2:
+			//x-current
+			if (m_start_inside[1] && m_start_inside[2])
+				for (unsigned int i=start[0]+1;i<=stop[0];++i)
+					current+=Eng->GetCurr(0,i,start[1],start[2]);
+			//y-current
+			if (m_stop_inside[0] && m_start_inside[2])
+				for (unsigned int i=start[1]+1;i<=stop[1];++i)
+					current+=Eng->GetCurr(1,stop[0],i,start[2]);
+			//x-current
+			if (m_stop_inside[1] && m_stop_inside[2])
+				for (unsigned int i=start[0]+1;i<=stop[0];++i)
+					current-=Eng->GetCurr(0,i,stop[1],stop[2]);
+			//y-current
+			if (m_start_inside[0] && m_stop_inside[2])
+				for (unsigned int i=start[1]+1;i<=stop[1];++i)
+					current-=Eng->GetCurr(1,start[0],i,stop[2]);
+			break;
+		default:
+			//this cannot happen...
+			return 0.0;
+			break;
+		}
 	}
 
 	return current;
diff --git a/FDTD/processcurrent.h b/FDTD/processcurrent.h
index 7eaff5c..e0ce15e 100644
--- a/FDTD/processcurrent.h
+++ b/FDTD/processcurrent.h
@@ -23,7 +23,7 @@
 class ProcessCurrent : public ProcessIntegral
 {
 public:
-	ProcessCurrent(Operator* op, Engine* eng);
+	ProcessCurrent(Operator* op);
 	virtual ~ProcessCurrent();
 
 	//! Integrate currents flowing through an area
diff --git a/FDTD/processfields.cpp b/FDTD/processfields.cpp
index 5a3c790..dc39a37 100644
--- a/FDTD/processfields.cpp
+++ b/FDTD/processfields.cpp
@@ -19,8 +19,9 @@
 #include <H5Cpp.h>
 #include "tools/global.h"
 #include "processfields.h"
+#include "engine_interface_fdtd.h"
 
-ProcessFields::ProcessFields(Operator* op, Engine* eng) : Processing(op, eng)
+ProcessFields::ProcessFields(Operator* op) : Processing(op)
 {
 	m_DumpType = E_FIELD_DUMP;
 	// vtk-file is default
@@ -212,30 +213,35 @@ void ProcessFields::DefineStartStopCoord(double* dstart, double* dstop)
 
 double ProcessFields::CalcTotalEnergy() const
 {
-	if (!Eng)
-		return 0;
+	double energy=0.0;
 
-	double energy=0;
-	unsigned int pos[3];
-	for (pos[0]=0;pos[0]<Op->GetNumberOfLines(0);++pos[0])
+	Engine_Interface_FDTD* EI_FDTD = dynamic_cast<Engine_Interface_FDTD*>(m_Eng_Interface);
+
+	if (EI_FDTD)
 	{
-		for (pos[1]=0;pos[1]<Op->GetNumberOfLines(1);++pos[1])
+		const Engine* Eng = EI_FDTD->GetFDTDEngine();
+
+		unsigned int pos[3];
+		for (pos[0]=0;pos[0]<Op->GetNumberOfLines(0);++pos[0])
 		{
-			for (pos[2]=0;pos[2]<Op->GetNumberOfLines(2);++pos[2])
+			for (pos[1]=0;pos[1]<Op->GetNumberOfLines(1);++pos[1])
 			{
-				energy+=fabs(Eng->GetVolt(0,pos[0],pos[1],pos[2]) * Eng->GetCurr(1,pos[0],pos[1],pos[2]));
-				energy+=fabs(Eng->GetVolt(0,pos[0],pos[1],pos[2]) * Eng->GetCurr(2,pos[0],pos[1],pos[2]));
-				energy+=fabs(Eng->GetVolt(1,pos[0],pos[1],pos[2]) * Eng->GetCurr(0,pos[0],pos[1],pos[2]));
-				energy+=fabs(Eng->GetVolt(1,pos[0],pos[1],pos[2]) * Eng->GetCurr(2,pos[0],pos[1],pos[2]));
-				energy+=fabs(Eng->GetVolt(2,pos[0],pos[1],pos[2]) * Eng->GetCurr(0,pos[0],pos[1],pos[2]));
-				energy+=fabs(Eng->GetVolt(2,pos[0],pos[1],pos[2]) * Eng->GetCurr(1,pos[0],pos[1],pos[2]));
+				for (pos[2]=0;pos[2]<Op->GetNumberOfLines(2);++pos[2])
+				{
+					energy+=fabs(Eng->GetVolt(0,pos[0],pos[1],pos[2]) * Eng->GetCurr(1,pos[0],pos[1],pos[2]));
+					energy+=fabs(Eng->GetVolt(0,pos[0],pos[1],pos[2]) * Eng->GetCurr(2,pos[0],pos[1],pos[2]));
+					energy+=fabs(Eng->GetVolt(1,pos[0],pos[1],pos[2]) * Eng->GetCurr(0,pos[0],pos[1],pos[2]));
+					energy+=fabs(Eng->GetVolt(1,pos[0],pos[1],pos[2]) * Eng->GetCurr(2,pos[0],pos[1],pos[2]));
+					energy+=fabs(Eng->GetVolt(2,pos[0],pos[1],pos[2]) * Eng->GetCurr(0,pos[0],pos[1],pos[2]));
+					energy+=fabs(Eng->GetVolt(2,pos[0],pos[1],pos[2]) * Eng->GetCurr(1,pos[0],pos[1],pos[2]));
+				}
 			}
 		}
 	}
 	return energy*0.5;
 }
 
-void  ProcessFields::SetSubSampling(unsigned int subSampleRate, int dir)
+void ProcessFields::SetSubSampling(unsigned int subSampleRate, int dir)
 {
 	if (dir>2) return;
 	if (dir<0)
diff --git a/FDTD/processfields.h b/FDTD/processfields.h
index 4fc186c..83ae51d 100644
--- a/FDTD/processfields.h
+++ b/FDTD/processfields.h
@@ -26,7 +26,7 @@
 class ProcessFields : public Processing
 {
 public:
-	ProcessFields(Operator* op, Engine* eng);
+	ProcessFields(Operator* op);
 	virtual ~ProcessFields();
 
 	enum FileType { VTK_FILETYPE, HDF5_FILETYPE};
diff --git a/FDTD/processfields_td.cpp b/FDTD/processfields_td.cpp
index 95968be..42edd7c 100644
--- a/FDTD/processfields_td.cpp
+++ b/FDTD/processfields_td.cpp
@@ -20,7 +20,7 @@
 #include <sstream>
 #include <string>
 
-ProcessFieldsTD::ProcessFieldsTD(Operator* op, Engine* eng) : ProcessFields(op, eng)
+ProcessFieldsTD::ProcessFieldsTD(Operator* op) : ProcessFields(op)
 {
 	pad_length = 8;
 }
@@ -40,7 +40,7 @@ int ProcessFieldsTD::Process()
 	if (m_fileType==VTK_FILETYPE)
 	{
 		stringstream ss;
-		ss << filePattern << std::setw( pad_length ) << std::setfill( '0' ) << Eng->GetNumberOfTimesteps() << ".vtk";
+		ss << filePattern << std::setw( pad_length ) << std::setfill( '0' ) << m_Eng_Interface->GetNumberOfTimesteps() << ".vtk";
 		filename = ss.str();
 	}
 	else
@@ -107,8 +107,8 @@ int ProcessFieldsTD::Process()
 	else if (m_fileType==HDF5_FILETYPE)
 	{
 		stringstream ss;
-		ss << std::setw( pad_length ) << std::setfill( '0' ) << Eng->GetNumberOfTimesteps();
-		DumpVectorArray2HDF5(filename.c_str(),string( ss.str() ),field,numLines,(0.5+Eng->GetNumberOfTimesteps())*Op->GetTimestep());
+		ss << std::setw( pad_length ) << std::setfill( '0' ) << m_Eng_Interface->GetNumberOfTimesteps();
+		DumpVectorArray2HDF5(filename.c_str(),string( ss.str() ),field,numLines,(0.5+m_Eng_Interface->GetNumberOfTimesteps())*Op->GetTimestep());
 	}
 	else
 		cerr << "ProcessFieldsTD::Process: unknown File-Type" << endl;
diff --git a/FDTD/processfields_td.h b/FDTD/processfields_td.h
index 99f4616..36e86ef 100644
--- a/FDTD/processfields_td.h
+++ b/FDTD/processfields_td.h
@@ -23,7 +23,7 @@
 class ProcessFieldsTD : public ProcessFields
 {
 public:
-	ProcessFieldsTD(Operator* op, Engine* eng);
+	ProcessFieldsTD(Operator* op);
 	virtual ~ProcessFieldsTD();
 
 	virtual int Process();
diff --git a/FDTD/processing.cpp b/FDTD/processing.cpp
index 95e6033..e952f83 100644
--- a/FDTD/processing.cpp
+++ b/FDTD/processing.cpp
@@ -21,10 +21,9 @@
 #include "time.h"
 #include <climits>
 
-Processing::Processing(Operator* op, Engine* eng)
+Processing::Processing(Operator* op)
 {
 	Op=op;
-	Eng=eng;
 	Enabled = true;
 	m_PS_pos = 0;
 	SetPrecision(12);
@@ -59,7 +58,7 @@ bool Processing::CheckTimestep()
 {
 	if (m_ProcessSteps.size()>m_PS_pos)
 	{
-		if (m_ProcessSteps.at(m_PS_pos)==Eng->GetNumberOfTimesteps())
+		if (m_ProcessSteps.at(m_PS_pos)==m_Eng_Interface->GetNumberOfTimesteps())
 		{
 			++m_PS_pos;
 			return true;
@@ -67,12 +66,12 @@ bool Processing::CheckTimestep()
 	}
 	if (ProcessInterval)
 	{
-		if (Eng->GetNumberOfTimesteps()%ProcessInterval==0) return true;
+		if (m_Eng_Interface->GetNumberOfTimesteps()%ProcessInterval==0) return true;
 	}
 
 	if (m_FD_Interval)
 	{
-		if (Eng->GetNumberOfTimesteps()%m_FD_Interval==0) return true;
+		if (m_Eng_Interface->GetNumberOfTimesteps()%m_FD_Interval==0) return true;
 	}
 	return false;
 }
@@ -83,11 +82,11 @@ int Processing::GetNextInterval() const
 	int next=INT_MAX;
 	if (m_ProcessSteps.size()>m_PS_pos)
 	{
-		next = (int)m_ProcessSteps.at(m_PS_pos)-(int)Eng->GetNumberOfTimesteps();
+		next = (int)m_ProcessSteps.at(m_PS_pos)-(int)m_Eng_Interface->GetNumberOfTimesteps();
 	}
 	if (ProcessInterval!=0)
 	{
-		int next_Interval = (int)ProcessInterval - (int)Eng->GetNumberOfTimesteps()%ProcessInterval;
+		int next_Interval = (int)ProcessInterval - (int)m_Eng_Interface->GetNumberOfTimesteps()%ProcessInterval;
 		if (next_Interval<next)
 			next = next_Interval;
 	}
@@ -95,7 +94,7 @@ int Processing::GetNextInterval() const
 	//check for FD sample interval
 	if (m_FD_Interval!=0)
 	{
-		int next_Interval = (int)m_FD_Interval - (int)Eng->GetNumberOfTimesteps()%m_FD_Interval;
+		int next_Interval = (int)m_FD_Interval - (int)m_Eng_Interface->GetNumberOfTimesteps()%m_FD_Interval;
 		if (next_Interval<next)
 			next = next_Interval;
 	}
@@ -165,58 +164,6 @@ void Processing::DefineStartStopCoord(double* dstart, double* dstop)
 	}
 }
 
-double Processing::CalcLineIntegral(unsigned int* start, unsigned int* stop, int field) const
-{
-	switch (field) {
-	case 0:
-		return CalcLineIntegral_V( start, stop );
-	case 1:
-		return CalcLineIntegral_I( start, stop );
-	}
-	return 0;
-}
-
-double Processing::CalcLineIntegral_I(unsigned int* start, unsigned int* stop) const
-{
-	double result=0;
-	for (int n=0;n<3;++n)
-	{
-		if (start[n]<stop[n])
-		{
-			unsigned int pos[3]={start[0],start[1],start[2]};
-			for (;pos[n]<stop[n];++pos[n])
-				result += Eng->GetCurr(n,pos[0],pos[1],pos[2]);
-		}
-		else
-		{
-			unsigned int pos[3]={stop[0],stop[1],stop[2]};
-			for (;pos[n]<start[n];++pos[n])
-				result -= Eng->GetCurr(n,pos[0],pos[1],pos[2]);
-		}
-	}
-	return result;
-}
-double Processing::CalcLineIntegral_V(unsigned int* start, unsigned int* stop) const
-{
-	double result=0;
-	for (int n=0;n<3;++n)
-	{
-		if (start[n]<stop[n])
-		{
-			unsigned int pos[3]={start[0],start[1],start[2]};
-			for (;pos[n]<stop[n];++pos[n])
-				result += Eng->GetVolt(n,pos[0],pos[1],pos[2]);
-		}
-		else
-		{
-			unsigned int pos[3]={stop[0],stop[1],stop[2]};
-			for (;pos[n]<start[n];++pos[n])
-				result -= Eng->GetVolt(n,pos[0],pos[1],pos[2]);
-		}
-	}
-	return result;
-}
-
 void Processing::OpenFile( string outfile )
 {
 	if (file.is_open())
diff --git a/FDTD/processing.h b/FDTD/processing.h
index cee5c25..bd74c99 100644
--- a/FDTD/processing.h
+++ b/FDTD/processing.h
@@ -33,7 +33,7 @@ typedef std::complex<double> double_complex;
 class Processing
 {
 public:
-	Processing(Operator* op, Engine* eng);
+	Processing(Operator* op);
 	virtual ~Processing();
 
 	//! Set the interface to the engine. Each processing needs its own engine interface. This class will take ownership and cleanup the interface on deletion!
@@ -85,7 +85,6 @@ public:
 protected:
 	Engine_Interface_Base* m_Eng_Interface;
 	Operator* Op;
-	Engine* Eng;
 	MeshType m_Mesh_Type;
 
 	unsigned int m_precision;
@@ -128,10 +127,6 @@ protected:
 	string m_filename;
 
 	virtual void OpenFile(string outfile);
-
-	double CalcLineIntegral(unsigned int* start, unsigned int* stop, int field) const;
-	double CalcLineIntegral_I(unsigned int* start, unsigned int* stop) const;
-	double CalcLineIntegral_V(unsigned int* start, unsigned int* stop) const;
 };
 
 class ProcessingArray
diff --git a/FDTD/processintegral.cpp b/FDTD/processintegral.cpp
index cc2321a..1944166 100644
--- a/FDTD/processintegral.cpp
+++ b/FDTD/processintegral.cpp
@@ -18,7 +18,7 @@
 #include "processintegral.h"
 #include <iomanip>
 
-ProcessIntegral::ProcessIntegral(Operator* op, Engine* eng)  : Processing(op, eng)
+ProcessIntegral::ProcessIntegral(Operator* op)  : Processing(op)
 {
 	m_TimeShift = 0.0;
 	m_Results=NULL;
@@ -56,11 +56,11 @@ int ProcessIntegral::Process()
 	int NrInt = GetNumberOfIntegrals();
 	double integral = m_Results[0] * m_weight;
 
-	double time = (double)Eng->GetNumberOfTimesteps()*Op->GetTimestep() + m_TimeShift;
+	double time = m_Eng_Interface->GetTime(false) + m_TimeShift;
 
 	if (ProcessInterval)
 	{
-		if (Eng->GetNumberOfTimesteps()%ProcessInterval==0)
+		if (m_Eng_Interface->GetNumberOfTimesteps()%ProcessInterval==0)
 		{
 			TD_Values.push_back(integral);
 			file << setprecision(m_precision) << time;
@@ -72,7 +72,7 @@ int ProcessIntegral::Process()
 
 	if (m_FD_Interval)
 	{
-		if (Eng->GetNumberOfTimesteps()%m_FD_Interval==0)
+		if (m_Eng_Interface->GetNumberOfTimesteps()%m_FD_Interval==0)
 		{
 			double T = time;
 			for (size_t n=0;n<m_FD_Samples.size();++n)
diff --git a/FDTD/processintegral.h b/FDTD/processintegral.h
index 63d49d7..961e706 100644
--- a/FDTD/processintegral.h
+++ b/FDTD/processintegral.h
@@ -51,7 +51,7 @@ public:
 	virtual int Process();
 
 protected:
-	ProcessIntegral(Operator* op, Engine* eng);
+	ProcessIntegral(Operator* op);
 
 	//! timeshift to be used in TD and FD data, e.g. 0.5*dT in case of current based parameter
 	double m_TimeShift;
diff --git a/FDTD/processmodematch.cpp b/FDTD/processmodematch.cpp
index 9c2bd7b..69b80ea 100644
--- a/FDTD/processmodematch.cpp
+++ b/FDTD/processmodematch.cpp
@@ -19,7 +19,7 @@
 #include "CSFunctionParser.h"
 #include "tools/array_ops.h"
 
-ProcessModeMatch::ProcessModeMatch(Operator* op, Engine* eng) : ProcessIntegral(op, eng)
+ProcessModeMatch::ProcessModeMatch(Operator* op) : ProcessIntegral(op)
 {
 	for (int n=0;n<2;++n)
 	{
diff --git a/FDTD/processmodematch.h b/FDTD/processmodematch.h
index eae6665..4104f7e 100644
--- a/FDTD/processmodematch.h
+++ b/FDTD/processmodematch.h
@@ -25,7 +25,7 @@ class CSFunctionParser;
 class ProcessModeMatch : public ProcessIntegral
 {
 public:
-	ProcessModeMatch(Operator* op, Engine* eng);
+	ProcessModeMatch(Operator* op);
 	virtual ~ProcessModeMatch();
 
 	virtual void InitProcess();
diff --git a/FDTD/processvoltage.cpp b/FDTD/processvoltage.cpp
index 187a5be..72f0ff0 100644
--- a/FDTD/processvoltage.cpp
+++ b/FDTD/processvoltage.cpp
@@ -18,7 +18,7 @@
 #include "processvoltage.h"
 #include <iomanip>
 
-ProcessVoltage::ProcessVoltage(Operator* op, Engine* eng) : ProcessIntegral(op, eng)
+ProcessVoltage::ProcessVoltage(Operator* op) : ProcessIntegral(op)
 {
 }
 
@@ -29,5 +29,5 @@ ProcessVoltage::~ProcessVoltage()
 double ProcessVoltage::CalcIntegral()
 {
 	//integrate voltages from start to stop on a line
-	return CalcLineIntegral(start,stop,0);
+	return m_Eng_Interface->CalcVoltageIntegral(start,stop);
 }
diff --git a/FDTD/processvoltage.h b/FDTD/processvoltage.h
index 59ac48e..4bec349 100644
--- a/FDTD/processvoltage.h
+++ b/FDTD/processvoltage.h
@@ -24,7 +24,7 @@
 class ProcessVoltage : public ProcessIntegral
 {
 public:
-	ProcessVoltage(Operator* op, Engine* eng);
+	ProcessVoltage(Operator* op);
 	virtual ~ProcessVoltage();
 
 	virtual double CalcIntegral();
diff --git a/openems.cpp b/openems.cpp
index c3fed9a..642578c 100644
--- a/openems.cpp
+++ b/openems.cpp
@@ -447,12 +447,12 @@ int openEMS::SetupFDTD(const char* file)
 			{
 				if (pb->GetProbeType()==0)
 				{
-					ProcessVoltage* procVolt = new ProcessVoltage(FDTD_Op,FDTD_Eng);
+					ProcessVoltage* procVolt = new ProcessVoltage(FDTD_Op);
 					proc=procVolt;
 				}
 				else if (pb->GetProbeType()==1)
 				{
-					ProcessCurrent* procCurr = new ProcessCurrent(FDTD_Op,FDTD_Eng);
+					ProcessCurrent* procCurr = new ProcessCurrent(FDTD_Op);
 					proc=procCurr;
 				}
 				else if (pb->GetProbeType()==2)
@@ -461,7 +461,7 @@ int openEMS::SetupFDTD(const char* file)
 					proc = new ProcessHField(FDTD_Op,FDTD_Eng);
 				else if ((pb->GetProbeType()==10) || (pb->GetProbeType()==11))
 				{
-					ProcessModeMatch* pmm = new ProcessModeMatch(FDTD_Op,FDTD_Eng);
+					ProcessModeMatch* pmm = new ProcessModeMatch(FDTD_Op);
 					pmm->SetFieldType(pb->GetProbeType()-10);
 					pmm->SetModeFunction(0,pb->GetAttributeValue("ModeFunctionX"));
 					pmm->SetModeFunction(1,pb->GetAttributeValue("ModeFunctionY"));
@@ -493,7 +493,7 @@ int openEMS::SetupFDTD(const char* file)
 	vector<CSProperties*> DumpProps = CSX.GetPropertyByType(CSProperties::DUMPBOX);
 	for (size_t i=0;i<DumpProps.size();++i)
 	{
-		ProcessFieldsTD* ProcTD = new ProcessFieldsTD(FDTD_Op,FDTD_Eng);
+		ProcessFieldsTD* ProcTD = new ProcessFieldsTD(FDTD_Op);
 		ProcTD->SetEnable(Enable_Dumps);
 		ProcTD->SetProcessInterval(Nyquist/m_OverSampling);
 
@@ -581,7 +581,8 @@ void openEMS::RunFDTD()
 	cout << "Running FDTD engine... this may take a while... grab a cup of coffee?!?" << endl;
 
 	//special handling of a field processing, needed to realize the end criteria...
-	ProcessFields* ProcField = new ProcessFields(FDTD_Op,FDTD_Eng);
+	ProcessFields* ProcField = new ProcessFields(FDTD_Op);
+	ProcField->SetEngineInterface(new Engine_Interface_FDTD(FDTD_Op,FDTD_Eng));
 	PA->AddProcessing(ProcField);
 	double maxE=0,currE=0;