I want to design a circuirt for Industrial Automation, which will use Power Line Communication to communicate with Master Controller
which will show status(On/Off) of remote located device(connected in the circuit).

Present system is based on Op-Amp FSK topology, giving lots of errors, working at 24VDC.

Please guide me new trend topology which will give error free solution to this system.

 

oooh! That is a tricky request.

I am tempted to say the two are mutually exclusive, i.e. power line communication and error free industrial automation.

For robust industrial automation, one has to incorporate error detection and correction.
RS-485 is more commonly used for industrial automation.

 

oooh! That is a tricky request.

I am tempted to say the two are mutually exclusive, i.e. power line communication and error free industrial automation.

For robust industrial automation, one has to incorporate error detection and correction.
RS-485 is more commonly used for industrial automation.

Thanks Mr.Chips for your reply.

System Description:
1. Its a 2~3 km long conveyor system which is using pull-cord and Belt sway switches installed at every 30m on both sides of conveyor for emergency stop. approx 100 switches
2. Whenever any switch operates, in control room it should display address and status of switch operated.
3. Control rooms is located 1.5 to 2 km away from conveyor.

I think RS-485 will not be feasible for this system.The sensor circuit should be installed for each switch and should give correct status at Control Room.

 

Why wouldn't RS-485 work?

A single CAT-5 cable run, each switch is a network node.
You could power the whole thing over the unused wires in the CAT-5 cable.
At low data rates, 2 KM is not hard to make work.

 

There are home automation devices out there quite capable of doing what you've requested. Specifically for illumination automation, but that could be adapted for your needs.
Have a read at this article, perhaps you can take it from there yourself.

 

How about indicator diodes on top of a pole at each switch station. And a spotting scope at the control room. Or make the offending switch blink. You could get real fancy and have all the other pole leds point and converge on the offending switch.

 

Error free transmission, with a scheme like cmartinez referenced, is a matter of using error detecting/correcting codes and/or multiple transmission of the same information.
You also send separate signals for switch open and switch closed.
With multiple transmission you just use a voting scheme, where multiple identical data values are sent, and a large majority have to agree before it is accepted as a valid signal by the microprocessor.
Multiple transmission with voting should be quite feasible since it would appear the data being sent changes infrequently.
How fast do you need to detect a switch position change?

 

Error free transmission, with a scheme like cmartinez referenced, is a matter of using error detecting/correcting codes and/or multiple transmission of the same information.
With multiple transmission you just use a voting scheme, where multiple identical data values are sent, and a large majority have to agree before it is accepted as a valid signal by the microprocessor.
Multiple transmission with voting should be quite feasible since it would appear the data being sent changes infrequently.

And then, of course, there are CRC algorithms that can vastly improve reliability, without sacrificing response time too much by redundantly sending the same data several times.

For example, I've been using the X8 + X5 + X4 + 1 CRC algorithm flawlessly for more than 20 years now.

 

Why wouldn't RS-485 work?

A single CAT-5 cable run, each switch is a network node.
You could power the whole thing over the unused wires in the CAT-5 cable.
At low data rates, 2 KM is not hard to make work.

Thank you guys for showing interest here. As per Sensacell suggestion I studied about RS-485 communications I would like to share rough diagram of my system network, which is using RS-485 communication. I have mentioned almost all needed information in diagram. Please tell me, what precautions should i take.

waiting for your valuable reply.

Thanks

 

Read these documents- both great primers to get started.

You have two challenges:

1) Physical Hardware- getting all the stuff to communicate, managing ground references, line terminations etc.
Don't forget transient voltage protection.

2) Software / data protocol- this is relatively simple in your case, data rates are going to be low, you could have the master poll the state of each node in sequence.