how can i read switch 50m away from my system???

[eng_ahmed22]

i need to read switchs 50m away from my system, how that could be electronically??
i need schematic to enable me to determine the switch status with my microcontroller.
thanks alot

 

[optech]

you should search RS485 protocol. With a microcontroller, you can control your switch with this protocol.

Maybe you can use only RS232 (serial port) protocol (in 2400 baud). But this protocol not good for long distances.

Here is a link about RS485: http://www.turkengineers.com/metin.php?metin=50

If you search with google, you can find a lots of information about this protocol.

 

[leomecma]

Use current transmitters at remote side (switches)... if your switch is press transmitte 20mA, if not transmitte 4mA. You can do it with a voltage-current converter, at another side you can use just a resistor to convert it again. But the RS485 is good suggestion...


leomecma

 

[yo5oqa]

I've made an application with 1 analog multiplexer CD4067 - 16 inputs for switches and 1 output which is connected to microcontroller through 1 comparator lm339 (one input is at 2.5 v and the other input to multiplexer); ... so I have 16 switches, some of them at over 100 m distance and works very well, no false readings...
If that's what you want, I'll search the schematic ...

 

[eng_ahmed22]

Thanks alot everybody for interrest
yes yo5oqa.
this is exactly what i want, this is excellent solution becouse the awitchs are distributed at different distances and locations.
waiting for your schematic.

thanks everybody

 

[yo5oqa]

Here is the schematic, it was a more complex project with PC interface to store some logs and display switches states, also to drive relays and flash leds ... but you can see how to connect only what you want to ...