diff --git a/f28p65x_cpu1_echoback_solution/ethercat_subdevice_cpu1_hal.c b/f28p65x_cpu1_echoback_solution/ethercat_subdevice_cpu1_hal.c
index 10158e3..bd48d2d 100644
--- a/f28p65x_cpu1_echoback_solution/ethercat_subdevice_cpu1_hal.c
+++ b/f28p65x_cpu1_echoback_solution/ethercat_subdevice_cpu1_hal.c
@@ -415,6 +415,65 @@ ESC_writeWord(uint16_t wordValue, uint16_t address)
     EINT;
 }
 
+
+
+void
+ESC_WriteOddWordISR(uint16_t wordValue, uint16_t address )
+{
+
+    volatile uint16_t first_write , second_write , byte1 , byte2;
+ 
+        // 0xff00 to get higher byte , example 0x1234 & 0xff00 = 1200 r
+
+        // lower value of wordValue , this will be the higher byte for the (addr -1) word.
+        byte1 = (wordValue & 0x00ff)<<8;  
+
+        
+        //get lower byte of previous word and or with lower byte of word
+        first_write = ((ESC_readWordISR(address-1) & 0x00ff) | byte1);
+
+        // higher msb byte of wordValue ,  this will be lower byte of (addr +1) word
+        byte2 = ((wordValue & 0xff00))>>8;
+        
+        //get higher byte of next word and OR with higher byte of addr+1 word.
+        second_write = (((ESC_readWordISR(address+1) & 0xff00))  | byte2 );
+       
+
+       
+        HWREGH(ESC_BASE + ((address-1) / 2U)) = first_write;
+        HWREGH(ESC_BASE + ((address+1) / 2U)) = second_write;
+    
+
+
+}
+
+//*****************************************************************************
+//
+// ESC_writeWord
+//
+//*****************************************************************************
+
+void
+ESC_WriteOddWord(uint16_t wordValue , uint16_t address)
+{
+    //
+    // Disables interrupts
+    //
+    DINT;
+  
+    //
+    // Write one 16-word into ESC memory
+    //
+    ESC_WriteOddWordISR(wordValue, address);
+
+    //
+    // Enable interrupts
+    //
+    EINT;
+}
+
+
+
 //*****************************************************************************
 //
 // ESC_setLed
diff --git a/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_hw.h b/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_hw.h
index 11fb727..403477a 100644
--- a/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_hw.h
+++ b/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_hw.h
@@ -62,6 +62,12 @@
 #define HW_EscWriteDWord(DWordValue, Address)      ESC_writeDWord(DWordValue, Address)
 #define HW_EscWriteDWordIsr(DWordValue, Address)   ESC_writeDWordISR(DWordValue, Address)
 #define HW_EscWriteWord(WordValue, Address)        ESC_writeWord(WordValue, Address)
+
+//new
+#define HW_EscWriteOddWord(byte, Address)        ESC_WriteOddWord(byte, Address)
+
+
+// new end.
 #define HW_EscWriteWordIsr(WordValue, Address)     ESC_writeWordISR(WordValue, Address)
 #define HW_EscWriteMbxMem(pData, Address, Len)     ESC_writeBlock(pData, Address, Len)
 
diff --git a/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_echoback_solution/mailbox.c b/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_echoback_solution/mailbox.c
index ae94564..3881664 100644
--- a/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_echoback_solution/mailbox.c
+++ b/f28p65x_cpu1_echoback_solution/f28p65x_cpu1_echoback_solution/mailbox.c
@@ -820,15 +820,31 @@ void MBX_CheckAndCopyMailbox( void )
         VARVOLATILE UINT16 smstate = 0x00;
         HW_EscReadWord(smstate,ESC_SYNCMAN_CONTROL_OFFSET);
         smstate = SWAPWORD(smstate);
+    
+        if(smstate & SM_STATUS_MBX_BUFFER_FULL){
 
-        if(smstate & SM_STATUS_MBX_BUFFER_FULL)
-        {
-            /*Unlock the mailbox SyncManger buffer*/
             u16dummy = 0;
-            HW_EscReadWord(u16dummy,(u16EscAddrReceiveMbx + u16ReceiveMbxSize - 2));
+            /*Unlock the mailbox SyncManger buffer*/
+                
+            if ((u16EscAddrReceiveMbx + u16ReceiveMbxSize - 2) & 1)
+            {
+                /* Odd mailbox size: addr+size-2 is odd, last byte is at addr+size-1 (even).
+                Must read that word to cover the last byte and unlock SM0. */
+                HW_EscReadWord(u16dummy, (u16EscAddrReceiveMbx + u16ReceiveMbxSize - 1));
+            }
+            else
+            {
+
+                HW_EscReadWord(u16dummy, (u16EscAddrReceiveMbx + u16ReceiveMbxSize - 2));
+            }
+
 
         }
 
+
+
+
+
         }
 
         /* in MBX_MailboxWriteInd the mailbox protocol will be processed */
@@ -872,8 +888,8 @@ UINT8 MBX_CopyToSendMailbox( TMBX MBXMEM *pMbx )
 /*ECATCHANGE_START(V5.13) MBX2*/
         /*Reset the not used mailbox memory*/
         {
-            UINT16 LastUsedAddr = u16EscAddrSendMbx + mbxSize + MBX_HEADER_SIZE;
-            UINT16 LastAddrToReset = (u16EscAddrSendMbx + u16SendMbxSize);
+            volatile UINT16 LastUsedAddr = u16EscAddrSendMbx + mbxSize + MBX_HEADER_SIZE;
+            volatile UINT16 LastAddrToReset = (u16EscAddrSendMbx + u16SendMbxSize);
             /*round down to last even 16bit address*/
             LastUsedAddr = LastUsedAddr & 0xFFFE;
             LastAddrToReset = (LastAddrToReset - 2) & 0xFFFE;
@@ -885,6 +901,18 @@ UINT8 MBX_CopyToSendMailbox( TMBX MBXMEM *pMbx )
                 HW_EscWriteWord(u16dummy, LastUsedAddr);
                 LastUsedAddr = LastUsedAddr + 2;
             }
+
+            //  changed  added to handle odd case.
+            if((u16EscAddrSendMbx + u16SendMbxSize - 2) & 0001){
+
+                LastUsedAddr = LastUsedAddr - 1;
+                HW_EscWriteOddWord(u16dummy, LastUsedAddr);
+
+            }
+
+
+
+
         }
 /*ECATCHANGE_END(V5.13) MBX2*/
 
@@ -916,7 +944,14 @@ UINT8 MBX_CopyToSendMailbox( TMBX MBXMEM *pMbx )
                 MEMCPY((UINT16 *)&u16dummy,(((UINT16 *)pMbx) + LastDataAddress),(2 - BytesLeft));
             }
 
-            HW_EscWriteWord(u16dummy, (u16EscAddrSendMbx + u16SendMbxSize - 2));
+            if((u16EscAddrSendMbx + u16SendMbxSize - 2) & 0001){
+                // odd length box.
+                HW_EscWriteOddWord(u16dummy, (u16EscAddrSendMbx + u16SendMbxSize - 2));
+
+            }else{
+                HW_EscWriteWord(u16dummy, (u16EscAddrSendMbx + u16SendMbxSize - 2));
+            }
+
         }
         }