Hi, I am using arduino nano. I use the C # desktop application to communicate arduino using a serial port. But someone else can change Arduino's software. I want to prevent the software from being installed with a hardware key. The software must be installed when the switch is turned on, and the software should not be installed when it is turned off. But in both cases serial communication should work. How can I do that. I used English, bad translation, google translation. 
There is a jumper on the Arduino board to enable/disable the reset on serial connect.
aarg:
There is a jumper on the Arduino board to enable/disable the reset on serial connect.
The OP's legitimate program might like to cause a reset.
@scrappy, what exactly are you trying to prevent?
If someone uploads a different Arduino program what harm will be caused?
...R
aarg:
There is a jumper on the Arduino board to enable/disable the reset on serial connect.
I want to do serial communication with computer. But I want to prevent programming.
Robin2:
The OP's legitimate program might like to cause a reset.@scrappy, what exactly are you trying to prevent?
If someone uploads a different Arduino program what harm will be caused?
...R
I have a project. I wrote a piece of software in the school that the teachers used. Teachers are opening RFID cards and computers with RFID cards. But students plug Arduino into different computers and change software to read the card and block serial communication and use the system in bad faith. My goal is serial communication, but do not load software. You can install the software with a hardware button.
scrappy:
But students plug Arduino into different computers and change software
Do you mean that there is only one Arduino shared among several students?
If so, it sounds like it would be unfair if you prevent them from using it?
On the other hand if they are just changing the program specially to annoy you I suspect the solution lies outside the realms of programming.
...R
scrappy:
I used English, bad translation, google translation.
And the translation is not making a lot of sense at all, but there is not a lot the forum can do about it.
Can you not find someone (a technically aware human) who can do the translation for you, it would help ?