Date: Monday, June 25 @ 16:40:12 EDT
I've designed this project last year for a company but they cancelled the rest of the work for some reason i don't know. Instead of having it rust in the dust, i'm sharing it with you.
The project is basically a communication network by using the RS485 physical layer. A master can address and control 254 slaves and see their sensory inputs.
To make it more secure, i've developed my own communication protocol instead of using many sources on the net. Sure i've read lots of them very carefully and examined the basics of this kind of networks. While running, the master continuously sends data packets to the network each carrying a target address. Every target system receive the same data and monitor the address. If the address belongs to itself the slave sends a repply packet carrying the sensory inputs of itself. If the address is a foreing one, the slave simply ignores the packet immediately and starts to look for new ones. In this scheme, the master can continuously scan the sensors of many slaves.
Two RS232 chips are seen at the schematic above though the version of proteus program i had then didn'T have the necessary RS485 drivers on its library. The current versions have that and many other new chips.
By the way, the design is initially made in the real world, not on proteus only. All of the circuit design work is made on breadboard. After the project is cancelled, the 4 boards full of components stayed aside for months, dusting. Then i've decided to redraw all circuitry on proteus for testing the program and saving the circuit schematic for future use. I was wondering if proteus would be able to run a bigger project like this. and yes, the project worked almost like its working on real microcontrollers. I recommend everyone to use proteus.
Click the links below to download project files