MODBUS RTU ON PIC 18F45K22

[LD-tecnico]

GOOD MORNING, I MADE A MODBUS COMMUNICATION PROGRAM OVER RS232 THAT WHEN COMPILED ON THE 16F887 WORKS PERFECTLY.
WHEN I RECOMPILE IT FOR THE PIC18F45K22, THE COMMUNICATION DOESN'T WORK AT ALL.
COMPARED TO THE PROGRAM THAT WORKED ON THE PIC 16F887, I ADDED THE UART PORT INITIALIZATION.
BUT IT DOESN'T WORK.
DO I NEED TO ADD FURTHER INSTRUCTIONS?