Create a specification and description language (SDL) diagram to model the details of your access control panel system. Start with the sdl diagram access control panel example included in SmartDraw and modify it to match your access control panel, or any other system you need to document.
Start
Validation
Code(cid, PIN)
cur_panel := sender
Idle
from Panel
to Central
UnlockDoor
OK
from Central
to cur_panel
NotOK
Access Control Panel