Yes, I have one other that's for Rx but it grabs a short 8 byte serial string once every 2 seconds.

INCLUDE "DT_INTS-18.bas" ; Base Interrupt System
INCLUDE "ReEnterPBP-18.bas" ; Include if using PBP interrupts
INCLUDE "Elapsed_INT-18.bas" ; Elapsed Timer Routines

ASM
INT_LIST macro ; IntSource, Label, Type, ResetFlag?
INT_Handler RX_INT, _Receive, PBP, yes
INT_Handler TMR1_INT, _ClockCount, PBP, yes
endm
INT_CREATE ; Creates the interrupt processor
ENDASM

@ INT_ENABLE RX_INT ; enable external (INT) interrupts
@ INT_ENABLE TMR1_INT ; enable external (INT) interrupts


15 seconds is a long time and is pretty consistient.