backplane with power, ethernet, seria and USB?

Discussion in 'The Projects Forum' started by GodG, Jun 3, 2016.

  1. GodG

    Thread Starter New Member

    Jun 3, 2016
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    Hi,

    I’m trying to build a midterm system between a costly and highly custom VPX and a platform where each board interfaces with one another by cables.

    for example:

    imagine I have an off the shelf mini-itx motherboard, a switch, and 2 network video encoders

    my idea is to have a back plane that would supply power, serial communication (if required) and network. I would have to build custom fixtures for each board and cables to interface between the board and the back plane but globally the total number of cables will be reduced.

    i have searched the internet for answers, mainly regarding to high speed connector and pcb layout but no answer was found.

    Could someone please help me? any input is welcome.
     
  2. dl324

    Distinguished Member

    Mar 30, 2015
    3,235
    619
    Welcome to AAC!

    I think you're looking card edge connectors (also called edge card).
    upload_2016-6-3_11-54-4.png

    This Molex connector is good to 25Gbps.
     
  3. GodG

    Thread Starter New Member

    Jun 3, 2016
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    0
    thks dl324
    yes, i'm searching for that.
    im going to deal with different kind of communications with different impedances. i need to carefull choose the connectors, thanks.
    also, trying to know is some sort of passive electronics is needed on the back plane.
     
  4. dl324

    Distinguished Member

    Mar 30, 2015
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    Depends on what you're routing through the back plane. If it's video, you can use stripline or microstrip technology to match impedance.
     
  5. GodG

    Thread Starter New Member

    Jun 3, 2016
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    thks dl324
    the signals im routing are
    ethernet,
    rs232
    rs485
    can
    i2c maybe
    pal/ntsc video
     
  6. GodG

    Thread Starter New Member

    Jun 3, 2016
    6
    0
    thks dl324

    do you have any aditional advice u can give me?
     
  7. dl324

    Distinguished Member

    Mar 30, 2015
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    Some of the signals you want to route require shielding. Depending on the distance you plan to route the signals, you may have issues with signal integrity.
     
  8. GodG

    Thread Starter New Member

    Jun 3, 2016
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    i would say that a maximum distance is 30-40 cm
     
  9. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,518
    1,247
    Done a loooooot of backplanes...

    What is the packaging environment? Rack mount, air cooled? Conformal coated/rugged deployed?
    What are the form factors of the switch and video encoders?
    It's not clear how you are interacting with the VPX system.
    Every signal type you listed can be run through standard DIN 41612 connectors as used in VME. Low cost, reliable as all get out. For higher speed Ethernet, VME64X includes a 2 mm connector per slot good for gigabit Ethernet.
    If you want controlled 75 ohm connections for the video, most of the big D-subminiature connector makers have combo versions with 50 0r 75 ohm coax contacts and guide pins for blind mating.

    What does the overall system do?
    Where are you located?

    ak
     
  10. GodG

    Thread Starter New Member

    Jun 3, 2016
    6
    0
    hi analogkid and thks,
    its a midterm between rack mount and a computer pc box (in this case its a fully aluminium case). im looking for passive colling with heatpipes going to the frame.

    conformal coated? if i get you right you are refering to some coating on the pcb right? if thats the case then no.
    rugged deployed ? yes im looking for something rugged.
    switch and video encoder have their own form factors not standard, from what i know.
    im not interacting with VPX, it was one of the options when searching for a solution.
    VME and VME64X used connectors seem a good solution. i just have to search for sizes because i dont have to much space available.
    measures about 30 wide x 45cm deep x 20cm tall (board loaded horizontally)
    in your opinion the best option would be to combine DIN 41612 and d-subminiature? is it possible or just a stupid idea?

    all of this is for a robot.
    im in portugal.
     
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