ethernet card pin states 1

[parallax]

hi,
I'm trying to make a circuit such that when I connect the device to the patch panel, it will understand if there is a
computer connected and if so it's working or not.
Assuming that I'm using a rj45 interface, I have found that
4 th and 5 th (7 th and 8 th also) pins of ethernet card is shorted on the board by default. This means that I can easily understand if there is a computer(ethernet card) at the end of the line by examining the short circuit. But I havent found a way to understand if the computer is working or not yet.I hope I have clearly defined the problem.
How can I solve this problem?

 

[okanyilmaz]

hacý valla ne desen haklýsýn

 

[goluman]

Hi man
Interesting problem,The way i see it you will have to design the circuit yourself.You have explained how you would detect the presence of a NIC by checking for the shorted pins.What i suggest now is that you find out the time each PC broadcasts.(in TCp/IP every PC broadcasts its presence to the switch every once in a while maybe every minute or two)I am not sure of this time period.So what you need to do is use a multimeter next to a NIC and check for the output voltage /current every time the PC broadcasts.Now you design a OP-AMP(operational Amplifier circuit if this voltage is in milli volts,or a V to I converter,if the NIC sources current.Then you design a LED with a current limier resistance etc,so that it glows every time the PC broadcasts....
Simple but i haventtried it out yet