diff --git a/FreeModbus/port/user_mb_app.c b/FreeModbus/port/user_mb_app.c
index 9d4cfd1..6607f1f 100644
--- a/FreeModbus/port/user_mb_app.c
+++ b/FreeModbus/port/user_mb_app.c
@@ -64,8 +64,17 @@ eMBRegInputCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNRegs )
         iRegIndex = ( int )( usAddress - usRegInStart );
         while( usNRegs > 0 )
         {
-            *pucRegBuffer++ = ( unsigned char )( pusRegInputBuf[iRegIndex] >> 8 );
-            *pucRegBuffer++ = ( unsigned char )( pusRegInputBuf[iRegIndex] & 0xFF );
+            //Determine the master or slave
+            if (bMBRunInMasterMode)
+            {
+            	pusRegInputBuf[iRegIndex] = *pucRegBuffer++ << 8;
+                pusRegInputBuf[iRegIndex] |= *pucRegBuffer++;
+            }
+            else
+            {
+				*pucRegBuffer++ = ( unsigned char )( pusRegInputBuf[iRegIndex] >> 8 );
+				*pucRegBuffer++ = ( unsigned char )( pusRegInputBuf[iRegIndex] & 0xFF );
+            }
             iRegIndex++;
             usNRegs--;
         }
@@ -94,7 +103,7 @@ eMBRegHoldingCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNRegs, eMBRegi
 {
     eMBErrorCode    eStatus = MB_ENOERR;
     int             iRegIndex;
-    USHORT *        usRegHoldingBuf;
+    USHORT *        pusRegHoldingBuf;
     UCHAR           REG_HOLDING_START;
     UCHAR           REG_HOLDING_NREGS;
     UCHAR           usRegHoldStart;
@@ -102,14 +111,16 @@ eMBRegHoldingCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNRegs, eMBRegi
     //Determine the master or slave
     if (bMBRunInMasterMode)
     {
-    	usRegHoldingBuf = usMRegHoldBuf[ucMBMasterSendAddress];
+    	pusRegHoldingBuf = usMRegHoldBuf[ucMBMasterSendAddress];
     	REG_HOLDING_START = M_REG_HOLDING_START;
     	REG_HOLDING_NREGS = M_REG_HOLDING_NREGS;
     	usRegHoldStart = usMRegHoldStart;
+    	//If mode is read,the master will wirte the received date to bufffer.
+    	eMode = MB_REG_WRITE;
     }
     else
     {
-    	usRegHoldingBuf = usSRegInBuf;
+    	pusRegHoldingBuf = usSRegInBuf;
     	REG_HOLDING_START = S_REG_INPUT_START;
     	REG_HOLDING_NREGS = S_REG_INPUT_NREGS;
     	usRegHoldStart = usSRegInStart;
@@ -125,8 +136,8 @@ eMBRegHoldingCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNRegs, eMBRegi
         case MB_REG_READ:
             while( usNRegs > 0 )
             {
-                *pucRegBuffer++ = ( unsigned char )( usRegHoldingBuf[iRegIndex] >> 8 );
-                *pucRegBuffer++ = ( unsigned char )( usRegHoldingBuf[iRegIndex] & 0xFF );
+				*pucRegBuffer++ = ( unsigned char )( pusRegHoldingBuf[iRegIndex] >> 8 );
+				*pucRegBuffer++ = ( unsigned char )( pusRegHoldingBuf[iRegIndex] & 0xFF );
                 iRegIndex++;
                 usNRegs--;
             }
@@ -137,8 +148,8 @@ eMBRegHoldingCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNRegs, eMBRegi
         case MB_REG_WRITE:
             while( usNRegs > 0 )
             {
-                usRegHoldingBuf[iRegIndex] = *pucRegBuffer++ << 8;
-                usRegHoldingBuf[iRegIndex] |= *pucRegBuffer++;
+                pusRegHoldingBuf[iRegIndex] = *pucRegBuffer++ << 8;
+                pusRegHoldingBuf[iRegIndex] |= *pucRegBuffer++;
                 iRegIndex++;
                 usNRegs--;
             }
@@ -169,7 +180,7 @@ eMBRegCoilsCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNCoils, eMBRegis
     eMBErrorCode    eStatus = MB_ENOERR;
     int             iRegIndex , iRegBitIndex , iNReg;
     iNReg =  usNCoils / 8 + 1;        //占用寄存器数量
-    UCHAR *         ucCoilBuf;
+    UCHAR *         pucCoilBuf;
     UCHAR           COIL_START;
     UCHAR           COIL_NCOILS;
     UCHAR           usCoilStart;
@@ -177,14 +188,16 @@ eMBRegCoilsCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNCoils, eMBRegis
     //Determine the master or slave
     if (bMBRunInMasterMode)
     {
-    	ucCoilBuf = ucMCoilBuf[ucMBMasterSendAddress];
+    	pucCoilBuf = ucMCoilBuf[ucMBMasterSendAddress];
     	COIL_START = M_COIL_START;
     	COIL_NCOILS = M_COIL_NCOILS;
     	usCoilStart = usMCoilStart;
+    	//If mode is read,the master will wirte the received date to bufffer.
+    	eMode = MB_REG_WRITE;
     }
     else
     {
-    	ucCoilBuf = ucSCoilBuf;
+    	pucCoilBuf = ucSCoilBuf;
     	COIL_START = S_COIL_START;
     	COIL_NCOILS = S_COIL_NCOILS;
     	usCoilStart = usSCoilStart;
@@ -201,7 +214,7 @@ eMBRegCoilsCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNCoils, eMBRegis
         case MB_REG_READ:
             while( iNReg > 0 )
             {
-				*pucRegBuffer++ = xMBUtilGetBits(&ucCoilBuf[iRegIndex++] , iRegBitIndex , 8);
+				*pucRegBuffer++ = xMBUtilGetBits(&pucCoilBuf[iRegIndex++] , iRegBitIndex , 8);
                 iNReg --;
             }
 			pucRegBuffer --;
@@ -215,11 +228,11 @@ eMBRegCoilsCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNCoils, eMBRegis
         case MB_REG_WRITE:
             while(iNReg > 1)									 //最后面余下来的数单独算
             {
-				xMBUtilSetBits(&ucCoilBuf[iRegIndex++] , iRegBitIndex  , 8 , *pucRegBuffer++);
+				xMBUtilSetBits(&pucCoilBuf[iRegIndex++] , iRegBitIndex  , 8 , *pucRegBuffer++);
                 iNReg--;
             }
 			usNCoils = usNCoils % 8;                            //余下的线圈数
-			xMBUtilSetBits(&ucCoilBuf[iRegIndex++] , iRegBitIndex  , usNCoils , *pucRegBuffer++);
+			xMBUtilSetBits(&pucCoilBuf[iRegIndex++] , iRegBitIndex  , usNCoils , *pucRegBuffer++);
 			break;
         }
     }
@@ -245,7 +258,7 @@ eMBRegDiscreteCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNDiscrete )
     eMBErrorCode    eStatus = MB_ENOERR;
 	int             iRegIndex , iRegBitIndex , iNReg;
 	iNReg =  usNDiscrete / 8 + 1;        //占用寄存器数量
-    UCHAR *         ucDiscreteInputBuf;
+    UCHAR *         pucDiscreteInputBuf;
     UCHAR           DISCRETE_INPUT_START;
     UCHAR           DISCRETE_INPUT_NDISCRETES;
     UCHAR           usDiscreteInputStart;
@@ -253,14 +266,14 @@ eMBRegDiscreteCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNDiscrete )
     //Determine the master or slave
     if (bMBRunInMasterMode)
     {
-    	ucDiscreteInputBuf = ucMDiscInBuf[ucMBMasterSendAddress];
+    	pucDiscreteInputBuf = ucMDiscInBuf[ucMBMasterSendAddress];
     	DISCRETE_INPUT_START = M_DISCRETE_INPUT_START;
     	DISCRETE_INPUT_NDISCRETES = M_DISCRETE_INPUT_NDISCRETES;
     	usDiscreteInputStart = usMDiscInStart;
     }
     else
     {
-    	ucDiscreteInputBuf = ucSDiscInBuf;
+    	pucDiscreteInputBuf = ucSDiscInBuf;
     	DISCRETE_INPUT_START = S_DISCRETE_INPUT_START;
     	DISCRETE_INPUT_NDISCRETES = S_DISCRETE_INPUT_NDISCRETES;
     	usDiscreteInputStart = usSDiscInStart;
@@ -271,15 +284,32 @@ eMBRegDiscreteCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNDiscrete )
     {
         iRegIndex    = ( int )( usAddress - usDiscreteInputStart ) / 8 ;    //每个寄存器存8个
 		iRegBitIndex = ( int )( usAddress - usDiscreteInputStart ) % 8 ;	   //相对于寄存器内部的位地址
-	    while( iNReg > 0 )
-        {
-			*pucRegBuffer++ = xMBUtilGetBits(&ucDiscreteInputBuf[iRegIndex++] , iRegBitIndex , 8);
-            iNReg --;
-        }
-		pucRegBuffer --;
-		usNDiscrete = usNDiscrete % 8;                     //余下的线圈数	
-		*pucRegBuffer = *pucRegBuffer <<(8 - usNDiscrete); //高位补零
-		*pucRegBuffer = *pucRegBuffer >>(8 - usNDiscrete);
+
+	    //Determine the master or slave
+	    if (bMBRunInMasterMode)
+	    {
+			/* Update current coil values with new values from the
+			 * protocol stack. */
+			while(iNReg > 1)									 //最后面余下来的数单独算
+			{
+				xMBUtilSetBits(&pucDiscreteInputBuf[iRegIndex++] , iRegBitIndex  , 8 , *pucRegBuffer++);
+				iNReg--;
+			}
+			usNDiscrete = usNDiscrete % 8;                            //余下的线圈数
+			xMBUtilSetBits(&pucDiscreteInputBuf[iRegIndex++] , iRegBitIndex  , usNDiscrete , *pucRegBuffer++);
+	    }
+	    else
+	    {
+			while( iNReg > 0 )
+			{
+				*pucRegBuffer++ = xMBUtilGetBits(&pucDiscreteInputBuf[iRegIndex++] , iRegBitIndex , 8);
+				iNReg --;
+			}
+			pucRegBuffer --;
+			usNDiscrete = usNDiscrete % 8;                     //余下的线圈数
+			*pucRegBuffer = *pucRegBuffer <<(8 - usNDiscrete); //高位补零
+			*pucRegBuffer = *pucRegBuffer >>(8 - usNDiscrete);
+	    }
     }
     else
     {