uint32_t master_ack;  //global
master_ack = CAN_RX_Master();      
if (master_ack == 1)
{
      //пришел сюда если optimization = Low
}
else //no response
{    //пришел сюда если optimization = High
}

uint32_t CAN_RX_Master(void){
uint32_t mot_num;
uint32_t opcode;
uint32_t pos;
uint32_t ack = 0;

if (can_params.message_received)
{
can_params.message_received = 0;

mot_num = (RxMessage.ExtId & 0xFF) - BASE_MOTOR_ID;
if (mot_num > MAX_MOTORS)
return 0;

opcode = (RxMessage.ExtId >> 8) & 0xFF;

switch (opcode)
{
case CAN_COM_GET_ALL :

motor_rt_params[mot_num].current = ((RxMessage.Data[1]<<8) | RxMessage.Data[0]);
motor_rt_params[mot_num].speed = ((RxMessage.Data[3]<<8) | RxMessage.Data[2]);
motor_rt_params[mot_num].position = ((RxMessage.Data[5]<<8) | RxMessage.Data[4]);
ack = 1;
break;

case CAN_COM_I_AM :
motor_rt_params[mot_num].ena = 1;
motor_rt_params[mot_num].mot_id = BASE_MOTOR_ID + mot_num;
ack = 1;
break;

case CAN_COM_IGET :
motor_rt_params[mot_num].current = ( RxMessage.Data[1]<<8) | RxMessage.Data[0]);
pos = CAN_IGET_POS;
ack = 1;
break;

case CAN_COM_PGET :
motor_rt_params[mot_num].position = (( RxMessage.Data[1]<<8) | RxMessage.Data[0]);
pos = CAN_PGET_POS;
ack = 1;
break;

case CAN_COM_VGET :
motor_rt_params[mot_num].speed = (( RxMessage.Data[1]<<8) | RxMessage.Data[0]);
pos = CAN_VGET_POS;
ack = 1;
break;
}

if (ack)
motor_rt_params[mot_num].rx_flags |= (1<<pos);

return ack;
}

void USB_LP_CAN1_RX0_IRQHandler(void)
{
  can_params.fifo_num = CAN_FIFO0;
  
  can_message_received = 1;

  CAN_Receive(CAN1, CAN_FIFO0, &RxMessage);
}