PIC code libraries
Text taken from Patrick Lidstone, at least two PIC libraries are currently available, see list after the introduction.
xAP for the PIC uses Microchip's MPLAB free assembler. The assembler offers an excellent simulator to assist with debugging, and in-circuit emulators are available for many PIC devices, although these are generally costly. A PIC assembler library is available which supports table driven parsing of xAP messages - the code is very compact, occupying around 500 bytes.
There are a number of Basic compilers around for the PIC, and although I don't have first hand experience of these, I believe that integrating the assembler library with these shouldn't be too difficult. If you have success, do let me know. PIC's typically interface to the network using a serial interface, so if you intend to run xAP applications on your ethernet network as well as on PIC devices, you'll need to set up a xAP serial bridge to pass messages between the two networks.
lidstone.net Assembly Assembly libraries
BAZAutomation Assembly xAP-485 Assembly library