thank you very much for your reply, I really appreciated.
I saw your project, actually I don't see many difference with my approach to the problem. Anyway, in my project I use a PSoC5LP (CY8C5868AXI-LP032), an UART [v2.50] and a Bootloader [v1.50].
As I wrote in the first post, I usually use bootloader with UART for a RS232 communication and I never had problems.
This time, the UART is setted for a RS485 communication at 19200 bps, with 2 wire, no flow control, and a tx enable pin.
With this settings, often there was CYRET_ERR_DATA error, something wrong was happening, sometimes it program for the first 3-4 rows, sometimes it give me error when programming is just started.
Now, the project works, but I have not written a post because I'm not sure about the solution: I simply changed the baud rate, from 19200 to 38400, this kind of solution have no sense.
Maybe, for the bootloader, the RS485 is less stable than the RS232? Maybe the TX enabled pin give some problems at certains baud rates?
If someone have a similar problem we could talk about it.