diff --git a/mac_receiver.c b/mac_receiver.c
index 6b7ffde..8dc3fe9 100644
--- a/mac_receiver.c
+++ b/mac_receiver.c
@@ -4,25 +4,6 @@
 #include <cstdint>
 #include <stdint.h>
 
-
-typedef union {
-	struct {
-		uint8_t sapi: 3;	// MSB
-		uint8_t addr: 4;
-		uint8_t nothing: 1;	// LSB
-	};
-	uint8_t raw;
-} Adresse;
-
-typedef union {
-	struct {
-		uint8_t ack: 1;			// MSB
-		uint8_t read: 1;
-		uint8_t checksum: 6;	// LSB
-	};
-	uint8_t raw;
-} Status;
-
 void send_DATA_IND(Adresse source, Adresse destination, uint8_t* dataFramePtr) {
 	struct queueMsg_t queueMsg;	// queue message
 	osStatus_t retCode;			// return error code
diff --git a/mac_sender.c b/mac_sender.c
index 4f669d4..b5303c1 100644
--- a/mac_sender.c
+++ b/mac_sender.c
@@ -10,7 +10,12 @@ const osMessageQueueAttr_t queue_macData_attr = {
 void MacSender(void *argument) {
 	struct queueMsg_t queueMsg;	// queue message
 	uint8_t* msg;
+	Adresse src;
+	Adresse dst;
+	uint8_t length;
+	Status status;
 	osStatus_t retCode;					// return error code
+	char* strPtr;
 
 	lastToken = osMemoryPoolAlloc(memPool, osWaitForever);
 	queue_macData_id = osMessageQueueNew(4, sizeof(struct queueMsg_t), &queue_macData_attr);
@@ -54,8 +59,8 @@ void MacSender(void *argument) {
 					osWaitForever);
 				CheckRetCode(retCode, __LINE__, __FILE__, CONTINUE);
 
-				// Send msg from internal queue if exist
-				while (osMemoryPoolGetCount(queue_macData_id) != 0) { // Message in Queue
+				// Send one msg from internal queue if exist
+				if (osMemoryPoolGetCount(queue_macData_id) != 0) { // Message in Queue
 					retCode = osMessageQueueGet(
 						queue_macData_id,
 						&queueMsg,
@@ -87,7 +92,35 @@ void MacSender(void *argument) {
 			// DATABACK MESSAGE
 			//----------------------------------------------------------------------
 			case DATABACK: {
+				src.raw = msg[0];
+				dst.raw = msg[1];
+				length = msg[2];
+				status.raw = msg[3+length];
 
+				if(status.read == 0) {
+					if(status.ack == 0) {
+						msg = osMemoryPoolAlloc(memPool, osWaitForever);
+						queueMsg.type = TO_PHY;
+						queueMsg.anyPtr = 
+
+					} else {
+
+					}
+
+				} else {
+					strPtr = osMemoryPoolAlloc(memPool, osWaitForever);
+					sprintf(strPtr, "Dest. %d couldn't read message from %d\0", dst.add+1, src.addr+1);
+					queueMsg.type = MAC_ERROR;
+					queueMsg.addr = src.addr;
+					queueMsg.sapi = src.sapi;
+					queueMsg.anyPtr = strPtr;
+					retCode = osMessageQueuePut(
+						queue_lcd_id,
+						&queueMsg,
+						osPriorityNormal,
+						osWaitForever);
+					CheckRetCode(retCode, __LINE__, __FILE__, CONTINUE);
+				}
 				break;
 			}
 			
@@ -135,7 +168,40 @@ void MacSender(void *argument) {
 			// DATA MESSAGE
 			//----------------------------------------------------------------------
 			case DATA_IND: {
+				dst.addr = queueMsg.addr;
+				dst.sapi = queueMsg.sapi;
+				dst.nothing = 0;
+				src.addr = gTokenInterface.myAddress;
+				src.sapi = queueMsg.sapi;
+				src.nothing = 0;
+				length = strlen(queueMsg.anyPtr);
 
+				if(dst.addr == BROADCAST_ADDRESS) {
+					status.read = 1;
+					status.ack = 1;
+				} else {
+					status.read = 0;
+					status.ack = 0;
+				}
+
+				msg = osMemoryPoolAlloc(memPool, osWaitForever);
+				msg[0] = src.raw;
+				msg[1] = dst.raw;
+				msg[2] = length;
+				memcpy(&msg[3], queueMsg.anyPtr, length);
+				status.checksum = Checksum(msg);
+				msg[3+length] = status.raw;
+
+				retCode = osMemoryPoolFree(memPool, queueMsg.anyPtr);
+				CheckRetCode(retCode, __LINE__, __FILE__, CONTINUE);
+				queueMsg.anyPtr = msg;
+				queueMsg.type = TO_PHY;
+				retCode = osMessageQueuePut(
+					queue_macData_id,
+					&queueMsg,
+					osPriorityNormal,
+					osWaitForever);
+				CheckRetCode(retCode, __LINE__, __FILE__, CONTINUE);
 				break;
 			}
 
diff --git a/main.h b/main.h
index d2711e3..7375580 100644
--- a/main.h
+++ b/main.h
@@ -118,3 +118,24 @@ struct queueMsg_t
 	uint8_t	addr;						///< the source or destination address
 	uint8_t sapi;						///< the source or destination SAPI
 };
+
+//--------------------------------------------------------------------------------
+// The mac control union
+//--------------------------------------------------------------------------------
+typedef union {
+	struct {
+		uint8_t sapi: 3;	// MSB
+		uint8_t addr: 4;
+		uint8_t nothing: 1;	// LSB
+	};
+	uint8_t raw;
+} Adresse;
+
+typedef union {
+	struct {
+		uint8_t ack: 1;			// MSB
+		uint8_t read: 1;
+		uint8_t checksum: 6;	// LSB
+	};
+	uint8_t raw;
+} Status;
\ No newline at end of file