I am using PIC Basic Pro (verson 2.47) and Micro Code Studio Plus to program two PIC18F252-I/SPs. Part of the program is to communicate between the two PICs, with Serin2 and Serout2 on PIC pins C4 and C5 as Tx and RX for two Laird AC4790 wireless radios.

Most of the time the communication works well, but sometimes it does not work at all with some PIC chips. I have recently had 4 out of 10 chips that I programmed not work on the serial communication, but the other input and outputs seem to work fine. I have used this program for several years with good results, but recently have had more problems. Any suggestions?