I asked before and I might have missed the answer, but... Wat *is* the value of what ever is called the "Vector number" ? According to the error messge it not in the 0-63 range at least. Is line 174 the line with "void __ISR()" below ? (Maybe 174 is an error code and 1 is the line no, but anyway) It must/should be possible to look up the value of the symbol _UART1B_VECTOR in some include file and verify it, not ? Jan-Erik. Chris Roper wrote 2011-11-21 21:25: > Just to be sure I renamed UART4 as UART1B in the line: > > void __ISR(_UART1B_VECTOR, ipl2) IntUart4Handler(void) > > and get the same error: > > uart_interrupt.c:174:1: error: Vector number must be an integer between 0= and 63 --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .