diff --git a/slsReceiverSoftware/slsReceiver/slsReceiver.cpp b/slsReceiverSoftware/slsReceiver/slsReceiver.cpp
index cd5ab551d..f044f7b7f 100644
--- a/slsReceiverSoftware/slsReceiver/slsReceiver.cpp
+++ b/slsReceiverSoftware/slsReceiver/slsReceiver.cpp
@@ -18,9 +18,8 @@ using namespace std;
 slsReceiver::slsReceiver(int argc, char *argv[], int &success){
 	//creating base receiver
 	cout << "SLS Receiver" << endl;
-	receiverBase = new slsReceiverUDPFunctions();
 	int tcpip_port_no=-1;
-
+	bool bottom = false;
 
 	
 	ifstream infile;
@@ -116,6 +115,31 @@ slsReceiver::slsReceiver(int argc, char *argv[], int &success){
 					}
 				}
 			}
+
+			//mode top:bottom
+			else if(!strcasecmp(argv[iarg],"-mode")){
+				if(iarg+1==argc){
+					cout << "no mode given after -mode in command line. Exiting." << endl;
+					success=FAIL;
+				}else{
+					if(!strcasecmp(argv[iarg+1],"bottom")){
+						cout<<"mode: bottom"<<endl;
+						bottom = true;
+						iarg++;
+					}else if(!strcasecmp(argv[iarg+1],"top")){
+						cout<<"mode: top"<<endl;
+						iarg++;
+					}
+					else{
+						cout << "could not decode port in command line. \n\nExiting." << endl;
+						success=FAIL;
+					}
+				}
+			}
+
+
+
+
 			else{
 				cout << "Unknown argument:" << argv[iarg] << endl;
 				success=FAIL;
@@ -130,9 +154,9 @@ slsReceiver::slsReceiver(int argc, char *argv[], int &success){
 		cout << "rx_tcpport:\t TCP Communication Port with the client. Default:1954. " << endl << endl;
 	}
 
-
+	receiverBase = new slsReceiverUDPFunctions(bottom);
 	if (success==OK)
-	  tcpipInterface = new slsReceiverTCPIPInterface(success,receiverBase, tcpip_port_no);
+	  tcpipInterface = new slsReceiverTCPIPInterface(success,receiverBase, tcpip_port_no, bottom);
 	  //tcp ip interface
 
 
diff --git a/slsReceiverSoftware/slsReceiver/slsReceiverTCPIPInterface.cpp b/slsReceiverSoftware/slsReceiver/slsReceiverTCPIPInterface.cpp
index ef854bc59..a3e4e9790 100644
--- a/slsReceiverSoftware/slsReceiver/slsReceiverTCPIPInterface.cpp
+++ b/slsReceiverSoftware/slsReceiver/slsReceiverTCPIPInterface.cpp
@@ -17,6 +17,9 @@
 #include <sstream>
 #include <fstream>
 #include <stdlib.h>
+#include <byteswap.h> //linux5
+#define be64toh(x) __bswap_64 (x) //linux5
+//#include <endian.h> //linux6
 using namespace std;
 
 
@@ -28,7 +31,7 @@ slsReceiverTCPIPInterface::~slsReceiverTCPIPInterface() {
 }
 
 
-slsReceiverTCPIPInterface::slsReceiverTCPIPInterface(int &success, slsReceiverBase* rbase, int pn):
+slsReceiverTCPIPInterface::slsReceiverTCPIPInterface(int &success, slsReceiverBase* rbase, int pn, bool bot):
 		myDetectorType(GOTTHARD),
 		receiverBase(rbase),
 		ret(OK),
@@ -38,7 +41,8 @@ slsReceiverTCPIPInterface::slsReceiverTCPIPInterface(int &success, slsReceiverBa
 		dynamicrange(16),
 		socket(NULL),
 		killTCPServerThread(0),
-		tenGigaEnable(0), portNumber(DEFAULT_PORTNO+2){
+		tenGigaEnable(0), portNumber(DEFAULT_PORTNO+2),
+		bottom(bot){
 
   int port_no=portNumber;
 
@@ -1336,7 +1340,7 @@ int	slsReceiverTCPIPInterface::eiger_read_frame(){
 		}
 
 		/**proper frame*/
-		else{
+		else{//cout<<"**** got proper frame ******"<<endl;
 
 			memcpy(origVal,raw,frameSize);
 			raw=NULL;
@@ -1344,12 +1348,11 @@ int	slsReceiverTCPIPInterface::eiger_read_frame(){
 			int c1=8;//first port
 			int c2=(frameSize/2) + 8; //second port
 			int retindex=0;
-			int irow,ibytesperpacket,irepeat;
-			int repeat=1;
+			int irow,ibytesperpacket;
 			int linesperpacket = (16/dynamicrange)* 1;// 16:1 line, 8:2 lines, 4:4 lines, 32: 0.5
 			int numbytesperlineperport=(EIGER_PIXELS_IN_ONE_ROW/EIGER_MAX_PORTS)*dynamicrange/8;//16:1024,8:512,4:256,32:2048
 			int datapacketlength = EIGER_ONE_GIGA_ONE_DATA_SIZE;
-
+			int total_num_bytes = 1040*(16*dynamicrange)*2;
 
 			if(tenGigaEnable){
 				linesperpacket = (16/dynamicrange)* 4;// 16:4 line, 8:8 lines, 4:16 lines, 32: 2
@@ -1357,55 +1360,106 @@ int	slsReceiverTCPIPInterface::eiger_read_frame(){
 			}
 			//if 1GbE, one line is split into two packets for 32 bit mode, so its special
 			else if(dynamicrange == 32){
-				repeat=2;
 				numbytesperlineperport = 1024;
 				linesperpacket = 1; //we repeat this twice anyway for 32 bit
 			}
 
+			if(!bottom){
 
-			for(irow=0;irow<EIGER_PIXELS_IN_ONE_COL/linesperpacket;++irow){
-				ibytesperpacket=0;
-				while(ibytesperpacket<datapacketlength){
-					for(irepeat=0;irepeat<repeat;irepeat++){//only for 32 bit mode, take 2 packets from same port
+				for(irow=0;irow<EIGER_PIXELS_IN_ONE_COL/linesperpacket;++irow){
+					ibytesperpacket=0;
+					while(ibytesperpacket<datapacketlength){
+						//first port
 						memcpy(retval+retindex ,origVal+c1 ,numbytesperlineperport);
 						retindex += numbytesperlineperport;
 						c1 += numbytesperlineperport;
-						if(repeat == 2) c1 += 16;
-					}
-					for(irepeat=0;irepeat<repeat;irepeat++){//only for 32 bit mode, take 2 packets from same port
-
+						if(dynamicrange == 32){
+							c1 += 16;
+							memcpy(retval+retindex ,origVal+c1 ,numbytesperlineperport);
+							retindex += numbytesperlineperport;
+							c1 += numbytesperlineperport;
+							c1 += 16;
+						}
+						//second port
 						memcpy(retval+retindex ,origVal+c2 ,numbytesperlineperport);
 						retindex += numbytesperlineperport;
 						c2 += numbytesperlineperport;
-						if(repeat == 2) c2 += 16;
+						if(dynamicrange == 32){
+							c2 += 16;
+							memcpy(retval+retindex ,origVal+c2 ,numbytesperlineperport);
+							retindex += numbytesperlineperport;
+							c2 += numbytesperlineperport;
+							c2 += 16;
+						}
+						ibytesperpacket += numbytesperlineperport;
+					}
+					if(dynamicrange != 32) {
+						c1 += 16;
+						c2 += 16;
 					}
-					ibytesperpacket += numbytesperlineperport;
-				}
-				if(repeat == 1) {
-					c1 += 16;
-					c2 += 16;
 				}
+
 			}
 
+			//bottom half module
+			else{
+				c1 = (frameSize/2) - numbytesperlineperport - 8 ;
+				c2 = total_num_bytes - numbytesperlineperport - 8;
 
-			int64_t temp;
+				for(irow=0;irow<EIGER_PIXELS_IN_ONE_COL/linesperpacket;++irow){
+					ibytesperpacket=0;
+					while(ibytesperpacket<datapacketlength){
+						if(dynamicrange == 32){
+							//first port first chip
+							c1 -= (numbytesperlineperport + 16);
+							memcpy(retval+retindex ,origVal+c1 ,numbytesperlineperport);
+							retindex += numbytesperlineperport;
+							//first port second chip
+							c1 += (numbytesperlineperport+16);
+							memcpy(retval+retindex ,origVal+c1 ,numbytesperlineperport);
+							retindex += numbytesperlineperport;
+							c1 -= (numbytesperlineperport*2+32);//1024*2+16*2
+							//second port first chip
+							c2 -= (numbytesperlineperport + 16);
+							memcpy(retval+retindex ,origVal+c2 ,numbytesperlineperport);
+							retindex += numbytesperlineperport;
+							//second port second chip
+							c2 += (numbytesperlineperport + 16);
+							memcpy(retval+retindex ,origVal+c2 ,numbytesperlineperport);
+							retindex += numbytesperlineperport;
+							c2 -= (numbytesperlineperport*2+32);
+						}else{
+							//first port
+							memcpy(retval+retindex ,origVal+c1 ,numbytesperlineperport);
+							retindex += numbytesperlineperport;
+							c1 -= numbytesperlineperport;
+							//second port
+							memcpy(retval+retindex ,origVal+c2 ,numbytesperlineperport);
+							retindex += numbytesperlineperport;
+							c2 -= numbytesperlineperport;
+						}
+						ibytesperpacket += numbytesperlineperport;
+					}
+					if(dynamicrange != 32) {
+						c1 -= 16;
+						c2 -= 16;
+					}
+				}
+
+			}
+
+			//64 bit htonl cuz of endianness
 			for(i=0;i<(1024*(16*dynamicrange)*2)/8;i++){
+				(*(((uint64_t*)retval)+i)) = be64toh(((uint64_t)(*(((uint64_t*)retval)+i))));
+			 /*
+			  int64_t temp;
 			  temp = ((uint64_t)(*(((uint64_t*)retval)+i)));
 			  temp = ((temp << 8) & 0xFF00FF00FF00FF00ULL ) | ((temp >> 8) & 0x00FF00FF00FF00FFULL );
 			  temp = ((temp << 16) & 0xFFFF0000FFFF0000ULL ) | ((temp >> 16) & 0x0000FFFF0000FFFFULL );
 			  temp =  (temp << 32) | ((temp >> 32) & 0xFFFFFFFFULL);
 			  (*(((uint64_t*)retval)+i)) = temp;
+			  */
 			}
-/*
-				 ( (((val) >> 56) & 0x00000000000000FF) | (((val) >> 40) & 0x000000000000FF00) | \
-				   (((val) >> 24) & 0x0000000000FF0000) | (((val) >>  8) & 0x00000000FF000000) | \
-				   (((val) <<  8) & 0x000000FF00000000) | (((val) << 24) & 0x0000FF0000000000) | \
-				   (((val) << 40) & 0x00FF000000000000) | (((val) << 56) & 0xFF00000000000000) )
-			*/
-			/*
-			for(i=0;i<(1024*(16*dynamicrange)*2)/4;i++)
-				                (*(((uint32_t*)retval)+i)) = htonl((uint32_t)(*(((uint32_t*)retval)+i)));
-			*/
 			arg = index-startIndex;
 		}
 	}
diff --git a/slsReceiverSoftware/slsReceiver/slsReceiverTCPIPInterface.h b/slsReceiverSoftware/slsReceiver/slsReceiverTCPIPInterface.h
index 423d0949a..ccd27c255 100644
--- a/slsReceiverSoftware/slsReceiver/slsReceiverTCPIPInterface.h
+++ b/slsReceiverSoftware/slsReceiver/slsReceiverTCPIPInterface.h
@@ -26,8 +26,9 @@ public:
 	 * @param succecc socket creation was successfull
 	 * @param rbase pointer to the receiver base
 	 * @param pn port number (defaults to default port number)
+	 * @param bot mode is bottom if true, else its a top half module
 	 */
-  slsReceiverTCPIPInterface(int &success, slsReceiverBase* rbase, int pn=-1);
+  slsReceiverTCPIPInterface(int &success, slsReceiverBase* rbase, int pn=-1, bool bot=false);
 
 	/**
 	 * Sets the port number to listen to. 
@@ -272,6 +273,9 @@ private:
 	/** port number */
 	int portNumber;
 
+	/** true if bottom half module for eiger */
+	bool bottom;
+
 
 protected:
 	/** Socket */
diff --git a/slsReceiverSoftware/slsReceiver/slsReceiverUDPFunctions.cpp b/slsReceiverSoftware/slsReceiver/slsReceiverUDPFunctions.cpp
index 388272b6b..aa9458377 100644
--- a/slsReceiverSoftware/slsReceiver/slsReceiverUDPFunctions.cpp
+++ b/slsReceiverSoftware/slsReceiver/slsReceiverUDPFunctions.cpp
@@ -31,13 +31,14 @@ using namespace std;
 
 
 
-slsReceiverUDPFunctions::slsReceiverUDPFunctions():
+slsReceiverUDPFunctions::slsReceiverUDPFunctions(bool bot):
 		thread_started(0),
 		eth(NULL),
 		latestData(NULL),
 		guiFileName(NULL),
 		guiFrameNumber(0),
-		tengigaEnable(0){
+		tengigaEnable(0),
+		bottom(bot){
 	for(int i=0;i<MAX_NUM_LISTENING_THREADS;i++){
 		udpSocket[i] = NULL;
 		server_port[i] = DEFAULT_UDP_PORTNO+i;
@@ -443,16 +444,12 @@ void slsReceiverUDPFunctions::setEthernetInterface(char* c){
 
 
 void slsReceiverUDPFunctions::setUDPPortNo(int p){
-	//for(int i=0;i<numListeningThreads;i++){
-		server_port[0] = p;
-	//}
+	server_port[0] = p;
 }
 
 
 void slsReceiverUDPFunctions::setUDPPortNo2(int p){
-	//for(int i=0;i<numListeningThreads;i++){
-		server_port[1] = p;
-	//}
+	server_port[1] = p;
 }
 
 
@@ -885,6 +882,15 @@ void slsReceiverUDPFunctions::copyFrameToGui(char* startbuf[], uint32_t fnum, ch
 
 int slsReceiverUDPFunctions::createUDPSockets(){
 
+	int port[2];
+	port[0] = server_port[0];
+	port[1] = server_port[1];
+
+	/** eiger specific */
+	if(bottom){
+		port[0] = server_port[1];
+		port[1] = server_port[0];
+	}
 
 	//if eth is mistaken with ip address
 	if (strchr(eth,'.')!=NULL)
@@ -897,14 +903,14 @@ int slsReceiverUDPFunctions::createUDPSockets(){
 		cout<<"warning:eth is empty.listening to all"<<endl;
 
 		for(int i=0;i<numListeningThreads;i++)
-			udpSocket[i] = new genericSocket(server_port[i],genericSocket::UDP,bufferSize);
+			udpSocket[i] = new genericSocket(port[i],genericSocket::UDP,bufferSize);
 	}
 	//normal socket
 	else{
 		cout<<"eth:"<<eth<<endl;
 
 		for(int i=0;i<numListeningThreads;i++)
-			udpSocket[i] = new genericSocket(server_port[i],genericSocket::UDP,bufferSize,eth);
+			udpSocket[i] = new genericSocket(port[i],genericSocket::UDP,bufferSize,eth);
 	}
 
 	//error
@@ -912,10 +918,10 @@ int slsReceiverUDPFunctions::createUDPSockets(){
 	for(int i=0;i<numListeningThreads;i++){
 		iret = udpSocket[i]->getErrorStatus();
 		if(!iret)
-			cout << "UDP port opened at port " << server_port[i] << endl;
+			cout << "UDP port opened at port " << port[i] << endl;
 		else{
 #ifdef VERBOSE
-			cout << "Could not create UDP socket on port " << server_port[i]  << " error:" << iret << endl;
+			cout << "Could not create UDP socket on port " << port[i]  << " error:" << iret << endl;
 #endif
 			return FAIL;
 		}
@@ -1351,7 +1357,7 @@ int slsReceiverUDPFunctions::startReceiver(char message[]){
 		cout << endl << message << endl;
 		return FAIL;
 	}
-	cout << "UDP socket(s) created successfully. 1st  port " << server_port[0] << endl;
+	cout << "UDP socket(s) created successfully." << endl;
 
 
 	if(setupWriter() == FAIL){
@@ -1540,9 +1546,9 @@ int slsReceiverUDPFunctions::startListening(){
 				expected = maxBufferSize - carryonBufferSize;
 			}
 
-#ifdef VERYDEBUG
+//#ifdef VERYDEBUG
 			cout << ithread << " *** rc:" << dec << rc << ". expected:" << dec << expected << endl;
-#endif
+//#endif
 
 
 
@@ -1954,9 +1960,9 @@ int i;
 #endif
 				pthread_mutex_unlock(&(status_mutex));
 
-#ifdef VERYDEBUG
+//#ifdef VERYDEBUG
 				cout << ithread << ": Frames listened to " << dec << ((totalListeningFrameCount[ithread]*numListeningThreads)/packetsPerFrame) << endl;
-#endif
+//#endif
 
 				//waiting for all listening threads to be done, to print final count of frames listened to
 				if(ithread == 0){
diff --git a/slsReceiverSoftware/slsReceiver/slsReceiverUDPFunctions.h b/slsReceiverSoftware/slsReceiver/slsReceiverUDPFunctions.h
index 20c5d7633..d0efecfc3 100644
--- a/slsReceiverSoftware/slsReceiver/slsReceiverUDPFunctions.h
+++ b/slsReceiverSoftware/slsReceiver/slsReceiverUDPFunctions.h
@@ -40,7 +40,7 @@ public:
 	/**
 	 * Constructor
 	 */
-	slsReceiverUDPFunctions();
+	slsReceiverUDPFunctions(bool bot);
 
 	/**
 	 * Destructor
@@ -768,6 +768,9 @@ private:
 	 * 2 we open, close, write file, callback does not do anything */
 	int cbAction;
 
+	/** true if bottom half module for eiger */
+	bool bottom;
+
 
 public: