One thing I'd do is complain about the way the specification is written. It's unintelligible.
Here, the circuit to be triggered by a circuit between the uC and the input will be set manually.
This is very ambivalent. At this point I'd already go back to the customer/manager and ask for clarification.
In addition, uC side will see 1 or 0 value according to the set voltage. (For example, in the adjusted circuit, it will see ~260V and 0 under ~260V, which is 1 above it.)
This is even worse, particularly the phrase about ~260 being 1 above ~260 and 0...??? Say what?
Communication will be provided with the processor via USB and USB
computer
It will be detected as COM PORT.
OK, this is quite clear and something that goes wrong in your schematic, as you're missing the connection between the microcontroller and the CH340 in your setup. I think they mean to say that communication should be possible between the uC and the computer over USB, so connect tx and rx of the CH340 to rx and tx of the uC.
The data received from the sensors will be kept in a function
This is technically simply wrong. A function does not keep data. Maybe they mean an object, as in object oriented programming. Or maybe they just mean that the uC should store the sensor readings in its memory somewhere, and it should be possible to retrieve those readings using a function. It seems they might mean both, as there's also mention further on of retrieving sensor data over USB.
When more than 65V is read from IN1
(Also for 220V on IN2): This is not very specific. Firstly, it's not specified if they mean AC or DC, but let's assume AC. In that case, it's not made explicit how long the excursion above 65 (resp 220V) must be before the system trips.
When an advance below 210 from IN3 is read
It must be my poor grasp of the English language that precludes me from understanding what an 'advance' is in terms of electrical engineering. I have no clue what they mean by this.
UDP datagrams will be sent over RS232.
Virtual udp socket will be opened on the usb-rs232 converter on Windows and data will be exchanged through that channel.
This, in combination with the block diagram, is not clear once again. It's specifically not clear if it should indeed be possible to connect another RS232 device to this system, or if it is sufficient (as the textual specification implies, but does not make explicit) that RS232 communication happens over the USB interface exclusively.
inputs will be saved to this file in minutes
What do they mean, 'in minutes'..? I hope it can be done in a few milliseconds, otherwise there's a severe performance problem. Or do they mean "sensor values should be updated and saved to this file every minute"?
If this is a homework assignment you received from a professor, and it is indeed handed to you written in English, i.e. exactly as you have sent it to us, then I would personally contact the professor and try to politely explain that the specifications document (s)he has provided is not sufficiently clear. If this does not help, you might want to contact the faculty so that they can put measures in place that the teaching staff gets access to the necessary language training needed to operate effectively in higher education.
Your schematic isn't optimal, but after reading these specifications, I really cannot blame you. It's really difficult to focus on the task at hand if you have to keep doing a kind of hermeneutical analysis of this cryptic text.