Detect BUS SHORT

[arunkish]

Hello All,

I am looking for a solution to protect PIC and keep the device working during Short Circuit. I have 10 devices connected to supply voltage +5v in series like this.

-----+5v--------D1--------D2-------D3 .............. D10
-------ve-----------------------------------------------|

If I have a shot circuit all the devices stops working. What I am planning to do is to have a device AFTER D3 named DX and if there is a short D1,D2 and D3 will continue to work and the +5v supply to the devices after DX will be terminated.

Now the question is how can i detect the short in the DX. Is there a method available?

Thanks in advance.

[temtronic]

Yes, I've used a variation of that since 1984 to allow communication in a network to continue even if the lines were cut or shorted.
It consists of a simple 'double ended' cabling system with 4 wires( power(2),com1(1) and com2(1). There are low power NC relays on each node tying com1 to com2, though each goes to a separate 'rcv' pin on the PIC.
Software is just as simple( remember this is 25 years old,still running), The Host sends the same data down both Com1 and Com2,then listens for the slaves responses. A simple compare deterines if there is a 'line fault'. If so, the Host commands the last good 'slaves' on both sides of the fault to open their relays thus isolating the 'shorted' line and slaves.The rest of the network will still work 100%.
This system runs about 15 miles on regular phone wires at low speed but is very,very reliable.Better than Ethernet,RS485,wireless1-wire,etc.Hackerproof as you control the data protocol,can run on 1 com wire.It is full duplex,interlaced,serial communications cheap to build, simple to code.