Hmmm,

Your first message stated that you had a problem with the Interrupt routine.

Now I can see that you didn't have any interrupt routines, even though you had enabled Interrupts. So what I said previously, doesn't apply.

As for the Maximum RS232 distance. The spec says 50ft max. But it really depends on the baud rate. I've run it up to 200' with 2400 baud.

If you put an RS485 convertor on both ends, you can go up to 4000'

Darrel