RTX51 Tiny Traffic

"If my board and my hex-file are ok, there must be a mistake by writing on the chip"

Not necessarily.

The software might be incompatible with your particular hardware - which might not show up in the simulator.

Are you sure that all your port assignments, pin assignments, etc, are correct?

Are you sure that you have correctly configured RTX51 for your specific target - including memory, clock spedd, etc?

You still haven't mentioned doing any debugging on this - just saying "it doesn't work" is pretty worthless!
Have you tried writing simple trace messages to the serial port? or using LEDs to show startup status, etc?

Have you tried just a really simple RTX application?

"Or my chip (AT89s52) cannot work with rtx"

The RTX51 Documentation will tell you what it requires of its target - have you checked?

"If my board and my hex-file are ok, there must be a mistake by writing on the chip"

Not necessarily.

The software might be incompatible with your particular hardware - which might not show up in the simulator.

Are you sure that all your port assignments, pin assignments, etc, are correct?

Are you sure that you have correctly configured RTX51 for your specific target - including memory, clock spedd, etc?

You still haven't mentioned doing any debugging on this - just saying "it doesn't work" is pretty worthless!
Have you tried writing simple trace messages to the serial port? or using LEDs to show startup status, etc?

Have you tried just a really simple RTX application?

"Or my chip (AT89s52) cannot work with rtx"

The RTX51 Documentation will tell you what it requires of its target - have you checked?

http://www.keil.com/support/man/docs/tr51/tr51_examples.htm