I want to arm and disarm a security system through a physical 4x4 keypad with a 4-digit code. it is possible in node red?
Almost certainly yes. How does the keypad interface with the computer?
I use Raspberry pi 3 b +. This is the interfece way : https://www.youtube.com/watch?v=yYnX5QodqQ4
Have you tried using the gpio nodes - can you see button presses in node-red debug?
There are videos (like this one) that may help.
Once you can get every button inputting values into node-red (just use debug nodes to see the values comming in) then we can help you construct the logic for using the inputs as a pass code.
i can't see the button pressed in debug. This is the single way?
See my balena project
This project is based on a python process that is posting mqtt messages whenever a key is pressed/hold/released. Of course Node-RED can subscribe to these mqtt messages.