diff --git a/Protocol/CAN.cpp b/Protocol/CAN.cpp
index 639ce67..c2b1777 100644
--- a/Protocol/CAN.cpp
+++ b/Protocol/CAN.cpp
@@ -14,7 +14,7 @@ void CAN::transmitMsg(Uint16 boxNumber, const CANMessage& message){
     p_MailBox->MDH.all = 0x0;
     p_MailBox->MDL.all = 0x0;
 
-    p_MailBox->MSGCTRL.bit.DLC = message.msgctrl.bit.DLC;
+    p_MailBox->MSGCTRL.bit.DLC = message.dataLength;
     p_MailBox->MDH.all = message.mdh.all;
     p_MailBox->MDL.all = message.mdl.all;
 
@@ -109,6 +109,7 @@ void CAN::updateTXMessage(Uint16 boxNumber, const CANMessage& message){ // TODO
     // Set change data request (CDR bit + MBOX number)
     p_CanRegs_->CANMC.all |= (128 + boxNumber);
 
+    // TODO Add lenght changing?
     p_MailBox->MDL.all = message.mdl.all;
     p_MailBox->MDH.all = message.mdh.all;
 
@@ -146,7 +147,7 @@ void CAN::sendRemoteRequest(Uint16 boxNumber){
 }
 
 
-bool CAN::receiveMsg(Uint16 boxNumber, CANMessage& rxMessage){ // TODO faults just return -1
+int16 CAN::receiveMsg(Uint16 boxNumber, CANMessage& rxMessage){ // TODO faults just return -1
     if (boxNumber > 31) { return -1; }
 
     Uint32 mboxControl(0);
@@ -156,11 +157,11 @@ bool CAN::receiveMsg(Uint16 boxNumber, CANMessage& rxMessage){ // TODO faults ju
     p_MailBox = &(p_CanMBoxes_->MBOX0) + boxNumber;
 
     bool isNewMessageInBox = p_CanRegs_->CANRMP.all & mboxControl;
-    if(!isNewMessageInBox) return -1;
+    if(!isNewMessageInBox) return -2;
 
     p_CanRegs_->CANRMP.all &= mboxControl;
 
-    rxMessage.msgctrl.all = p_MailBox->MSGCTRL.all;
+    rxMessage.dataLength = p_MailBox->MSGCTRL.all;
     rxMessage.mdl.all = p_MailBox->MDL.all;
     rxMessage.mdh.all = p_MailBox->MDH.all;
 
@@ -171,7 +172,7 @@ bool CAN::receiveMsg(Uint16 boxNumber, CANMessage& rxMessage){ // TODO faults ju
     lostMessage = p_CanRegs_->CANRML.all & mboxControl;
 
     if(newMessage || lostMessage) {
-        return -1;
+        return -3;
     }
 
     return 0;
diff --git a/Protocol/CAN.h b/Protocol/CAN.h
index dfd1c2f..f38226c 100644
--- a/Protocol/CAN.h
+++ b/Protocol/CAN.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "DSP2833x_Device.h"
 #include "DSP28x_Project.h"
 
 namespace canSpace {
@@ -36,7 +37,8 @@ enum configSystemIsrFlags{
 struct MsgCtrlBits {     // bits  description
     Uint16      DLC:4;             // 0:3
     Uint16      RTR:1;             // 4
-    Uint16      rsvd1:3;           // 7:5   reserved
+    Uint16      OPC:1;             // 1
+    Uint16      rsvd1:2;           // 7:6   reserved
     Uint16      TPL:5;             // 12:8
     Uint16      rsvd2:3;           // 15:13 reserved
 };
@@ -86,7 +88,7 @@ union MsgID {
 
 
 struct CANMessage {
-    union MsgCtrlReg msgctrl;
+    Uint16 dataLength;
     union CANMDL_REG mdl;
     union CANMDH_REG mdh;
 
@@ -116,7 +118,7 @@ public:
     void transmitMsg(Uint16 boxNumber, const Uint32& message, const Uint16 dlc);
     void updateTXMessage(Uint16 boxNumber, const CANMessage& message);
     void sendRemoteRequest(Uint16 boxNumber);
-    bool receiveMsg(Uint16 boxNumber, CANMessage& rxMessage);
+    int16 receiveMsg(Uint16 boxNumber, CANMessage& rxMessage);
 
 private:
     CAN_VARIANT canPort;
diff --git a/Protocol/CANConfig.cpp b/Protocol/CANConfig.cpp
index a83daec..5eface1 100644
--- a/Protocol/CANConfig.cpp
+++ b/Protocol/CANConfig.cpp
@@ -252,9 +252,11 @@ void CAN::configRxMBox(Uint16 boxNumber, const MsgID& configID, const MsgCtrlReg
 
     // Overwrite protection
     // If "ON" make sure that an additional mailbox is configured to store ’overflow’ messages.
-    // CanShadow_.CANOPC.all = p_CanRegs_->CANOPC.all;
-    // CanShadow_.CANOPC.all |= mboxControl;                // Should be one more mailbox to store 'overflow' messages
-    // p_CanRegs_->CANOPC.all = CanShadow_.CANOPC.all;
+    if(configCtrlReg.bit.OPC){
+        CanShadow_.CANOPC.all = p_CanRegs_->CANOPC.all;
+        CanShadow_.CANOPC.all |= mboxControl;
+        p_CanRegs_->CANOPC.all = CanShadow_.CANOPC.all;
+    }
 
     // Enable Mailbox
     CanShadow_.CANME.all = p_CanRegs_->CANME.all;
diff --git a/main.cpp b/main.cpp
index e63ac35..7334870 100644
--- a/main.cpp
+++ b/main.cpp
@@ -88,7 +88,7 @@ void main()
 
     CpuTimer0.RegsAddr->TCR.bit.TSS = 0;
 
-    message.msgctrl.bit.DLC = 8;
+    message.dataLength = 8;
     message.mdl.byte.BYTE0 = 0x11;
     message.mdl.byte.BYTE1 = 0x22;
     message.mdl.byte.BYTE2 = 0x33;
@@ -157,9 +157,12 @@ interrupt void canb_isr(void){
     canISRcounter++;
 
     CANGIF0_REG CANGIF0_SHADOW;
+    volatile Uint32 resetBit;
+
     CANGIF0_SHADOW.all = ECanbRegs.CANGIF0.all;
 
     if (CANGIF0_SHADOW.bit.WLIF0){
+        resetBit = 256;
         ECanbRegs.CANGIF0.all = 256ul;
     }