Ethernet Hub to NIC connection tech question

Discussion in 'Computer Information' started by Terry, Jul 9, 2009.

  1. Terry

    Terry Guest

    If this isn't the appropraie group, someone plse direct me?

    I am attempting to build a data-stream detection circuit. Just see if
    the stream is there, or not. Use none of the data.

    This first attempt uses the transformer chip from a defunct NIC for
    the interface between my LAN and my circuit. CAT-5 connects between a
    powered hub port and an RJ-45 pins 3 and 6 connect to the transformer.
    I measure about 2 ohms across the transformer winding.

    The "Link-OK" lamp doesn't illuminate on the hub. A running PC plugged
    into that hub port does cause the LED to light.

    My question is: Why does the NIC in the PC light the indicator, but my
    circuit/XFMR will not (pulled from same typ NIC). The original
    connection shows direct connections of pins 3 and 6 to the
    transformer. No other componets connected tothose traces.

    I have a feeling there's more to the detection of the NIC
    (transformer) than meets the eye, for when I power down the PC on the
    same hub, it takes 10 sec for the "Link-OK" LED on the hub to go out.

    Any help would make my day!

    Cheers--
    Terry--WB4FXD
    Edenton, NC
     
    Terry, Jul 9, 2009
    #1
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  2. Stupid question here ...

    Can't you just plug the NIC into the hub or router, then check the Status of
    the resulting connection and watch the packet count as the stream comes down
    the wire? Set the Network Icon to display on the Tool Tray, then right-click
    and select Status.
     
    Jeff Strickland, Jul 9, 2009
    #2
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  3. Terry

    Terry Guest

    On Thu, 9 Jul 2009 08:39:37 -0700, "Jeff Strickland"

    =>Stupid question here ...
    =>
    =>Can't you just plug the NIC into the hub or router, then check the
    Status of
    =>the resulting connection and watch the packet count as the stream
    comes down
    =>the wire? Set the Network Icon to display on the Tool Tray, then
    right-click
    =>and select Status.

    No question is stupid, Jeff! But, no. The NIC is defunct, dead,
    shuffled off this mortal coil (C Python).

    I am trying to detect the presence or absence of the data stream
    without having to have a PC on line 24/7. I thought I could merely
    detect and rectify the stream and then do the logic I need from there.
    Evidently not.

    How does one detect something is connected? If handshaking is
    involved, then I'm dead in the water and will proceed accordingly.

    Thanks--
    Terry--WB4FXD
    Edenton, NC
     
    Terry, Jul 9, 2009
    #3
  4. My machines are connected to a router, some machines are wired and others
    are wireless.

    The router has lights on the front that tell me data is passing through it.
    The wired connections each have their own light, but the wireless
    connections all share the same light. In the case of the wireless
    connections, I know data is passing, I just don't know where. For the wired
    connections, I know which connection is active and which is not. I know the
    router is talking to the outside world because there is a light that blinks.
    I know it is talking internally because there are different lights that
    blink.

    I'm not sure there would be a data stream if there wasn't something there to
    receive it -- why send data where there is nothing to listen for it? When
    data passes, the receiver has to send data back to tell the sender that the
    data got there so the next packet will be sent. If there is no echo of the
    data sent out, the router or hub should not send any more data on that line
    until it gets a clue that there is something there to receive it. I think
    this means you have to have a machine connected for there to be a stream in
    the first place. My router has the lights OFF for the wired connections that
    are not connected, or are turned off.

    At the very least, the router sends out a heartbeat on the active lines, and
    when the heartbeat does not come back, the line goes off so the router does
    not waste time with an open line that is not listening anyway.

    I don't know how your Hub works, but logic says it should work similarly --
    it should monitor the heartbeat and go silent on any line where the
    heartbeat does not come back, and blink a light where the heartbeat is
    active. You _might_ have QoS settings that affect this, I'm not sure on that
    point.
     
    Jeff Strickland, Jul 9, 2009
    #4

  5. When I said that, I was referring to connecting the CAT5 cable to the PC and
    the hub, not physically installing the NIC in the hub.
     
    Jeff Strickland, Jul 9, 2009
    #5
  6. Terry

    Terry Guest

    On Thu, 9 Jul 2009 09:30:33 -0700, "Jeff Strickland"

    =>When I said that, I was referring to connecting the CAT5 cable to
    the PC and the hub, not physically installing the NIC in the hub.

    Yes, I understand. However, I am trying to get away from the necessity
    for a PC to be sitting there idling away 24/7. Build a .bat and ping
    every so often. If I get a return, wait and ping again later. If no
    return, ping a few more times and if still no joy throw up a flag. But
    that takes a confuser.

    Thanks for the help and suggestions. I think I'll go mow the lawn.
    Then I'll know exactly what I'm doing for the first time today!

    Cheers
    Terry--WB4FXD
    Edenton, NC
     
    Terry, Jul 9, 2009
    #6
  7. Terry

    Baron Guest

    I suspect you have answered your own question ! Google CSCD (carrier
    sense collision detection).
     
    Baron, Jul 9, 2009
    #7
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