Need Help:Microprocessor Based Railway Control System

[mahmudur85]

Hi
I want to build a railway control system which is control by microprocessor. I need some ideas.Can anybody please help me with some ideas about this.

I found an article on the web that suggested Intel 8085 microprocessor. What do you think?

plz reply soon if someone have some ideas......!

 

[RadioRon]

What do you want the system to do?

What programming languages are you able to work with?

Can you use a standard desktop PC as the microprocessor?

 

[mahmudur85]

reply to RadioRon: Microprocessor Based Railway Control System

Thank you RadioRon for your reply,
I had some test...so i could not reply on time.
I want to control the signal of a railway crossing. I also want include a system that can shift a moving train to a secondary line if another train is coming form the opposite direction. Which Train will be shifted is depend on the priority's of the trains.

** I am more or less familiar with C/C++. Is it enough or do i need to learn some other programming language.< >

i am an undergraduate student of EEE. Just completed 2nd year.

Thank you again.

 

[RadioRon]

If it is within the rules of this assignment to use a desktop PC as your controller, then C++ is fine. For that matter, even if you use a small microprocessor like 8085 or even PIC or AVR series, it is still OK to use C++ because usually you can find a compiler for the target uP. Usually the uP is chosen based on
- how many inputs and outputs and what type (ie. binary logic, A/D, D/A)
- what internal processes will be needed (timer? DSP?)
- what speed will be needed to execute your code in "real time"
- do you need a RTOS for the project (Real Time Operating System) or not?
- how much memory is needed to house the program code and variables and stack storage

The main thing you must do now is define in more detail what it means to say "control the signal of a railway crossing." You must define the devices that are being controlled, and you must define the inputs to the system, like train sensors for example. Once you have the inputs and outputs defined, you must design the logical flow of your program to do what is needed.

Once you have flow charted your program (or coded it in some sort of plain language psuedo-code) you must estimate what kind of subprograms you will need. For example, will you need floating point arithmetic? Or serial port protocol support?

You can also estimate how much time is available for the major input to output delays and this helps you guess the speed of the uP.

 

[Ambient]

C should be enough, but some assembly would be good. Assembly is pretty easy though. Would this happen to be for a model train?

Also, you will need to figure out how the control unit will figure out which train has highest priority. Is priority determined by where the train came from, where it is going, or just which train it is?

 

[Stellarcore]

An interesting setup I've heard of for controlling model railroads is to modify the locomotives so that they dont just feed the power from the tracks directly to the motor, instead they use the the tracks to power a micro on the engine. Then you send "commands" to the micro on the engine by modulating the power on the tracks. The power circuitry on the engine needs to have a big cap or something so that the engine always has power.

The advantage of this is that you can then have multiple engines on the same track being controlled independantly. You can use PWM on the micro to control the speed and an H-Bridge to control the direction. You could also modify your electric switches and control them the same way as the engines.

Then you just need to have a main controller or computer setup on the track side of things that manages all of the trains. If you want to automatically negotiate switching, you would also need some mechanism to locate the trains. I'm not sure how you could make the communication between trains "two way", but I'm sure something could be arranged. Or you could setup some kind of sensors at various points on the track, but then you would have to find a way to identify specific trains... Maybe RFID?

When I had a model railroad many years ago it was a relatively simple setup where the tracks powered the motors directly, meaning that every engine on the track did the same thing. And there were a few simple tricks that i had setup, for instance there was a section of track that crossed the middle and would turn the train around in the other direction, and it had to be electrically isolated. To turn the train around you would line up the polarity of the tracks as the train crossed on to the new section, and then when the engine is on the new section, flip the polarity of the other section so that when the train hits the main track again its going the right direction.

 

[blueroomelectronics]

It's called DCC
https://www.merg.org.uk/resources/dcc.htm