This is the extantion of the interrupt function, but steel according to the debugger ArrLen and chr stay at their init values after the assignment.
void SerialPort(void) interrupt 4 using 2
{
if (RI == 1)
{
if(ArrLenFlag==0) // The first value.
{
ArrLen = SBUF;
ArrLenFlag = 1;
}
else
{
if(SBUF=='S')// The start char.
{
Start_bit = 1;
SaveData(1000);
SaveData(1000); }
else
{
chr = SBUF;
SaveData(chr);data.
}
}
RI = 0;
}
}

Thank you very much for your help