Hi Ralph,

> The RX-Module Data output pin idles LOW, so Im using TRUE polarity (Mode $432D).

$432D or 17197d is actually inverted mode, but that's what you want anyhow if the receiver output idles low.

The problem with using inverted mode with SERIN2 and the timeout/label options is that positive going noise spikes on the serial input pin will *reset* the timeout period, and execution never jumps to the timeout label since there appears to be valid serial data inbound before the timeout period can expire.

I find sometimes just adding a 100K pull-down resistor to the receiver output helps reduce noise to a level that allows the timeout period to expire. If this isn't enough I may shift to an input pin on portc with Schmitt trigger input buffers to help cancel the noise spikes output by the receiver.

The input pin with the Schmitt trigger buffer is less suceptible to noise than TTL inputs. Most PIC peripherals like RB0/INT, CCP, and several others are Schmitt trigger buffered inputs to keep noise from triggering the peripheral functions.

You don't mention which pin you're using on the 18F or 16F parts, but that may be why it works on one, and not on the other?