Help hooking up "open drain" output

Discussion in 'The Projects Forum' started by MattATI, Mar 1, 2010.

  1. MattATI

    Thread Starter New Member

    Mar 1, 2010
    Ok, here is my issue. I have a electric motor. Motor has some I/O build in.
    Here are the functions:
    1. Pot +
    2. Signal Common
    3. Pot -
    4. Vc
    5. Enable
    6. Direction
    7. Reset
    8. Fault
    9. Speed monitor
    These are all the connections on the motor pinout.

    I need to be able to use FAULT signal and energize coil to show the condition when motor stalls or the supply voltage is too low.
    The output line (OPEN DRAIN) will go low when drive is experiencing fault condition. When the drive is operational, this output can be pulled high.
    I am confused on how should I hook everything up to work right.
    Essentially I need to have this line (FAULT) turn on or off coil inside of the relay.
    Any help appreciated ;)
  2. SgtWookie


    Jul 17, 2007
    I know you tried to supply a fair amount of information, but the posted info raises many questions. Do you have the datasheet for the motor, or at least a manufacturer and part number?

    You say "energize coil" - I suppose you're talking about a relay that is separate from the motor.

    An "open drain" is referring to a MOSFET that can sink current, but cannot source current. You could use such an open drain to sink current from a relay's coil, depending on the ratings of the open drain output, type/ratings of relay, etc. The relay would likely be used to open the coil circuit of another "latched" relay to prevent the circuit from powering up until the problem was manually corrected.
  3. MattATI

    Thread Starter New Member

    Mar 1, 2010
    Well ,the motor is an MCG motor MA34236.
    Its a brushless motor with 110Vac input to drive the motor and control lines I've mentioned on a separate cable.
    Here is the link
    Yes, the coils I want to energize is external - its mounted in my control cabinet.
    Thank you for all your help,
  4. SgtWookie


    Jul 17, 2007
    Do you know that they have a technical support group?
    Links to tech support are on that page.

    There is not enough information supplied in the installation manual to determine what the rating (current and voltage) of this open-collector output is. Your supply for the coil would need to share a common with the motor, but it can't be determined from the installation manual whether signal ground or earth ground is what is common to the open-drain fault output.

    Rather than risking damage by connecting it up incorrectly, you should contact their technical support, explain what you wish to do, and they should be able to tell you the best way to accomplish it.
  5. rjenkins

    AAC Fanatic!

    Nov 6, 2005
    The data sheets are not very helpful.

    One thing I noticed is a warning that the signal cables are LIVE to the AC supply and the entire control circuit must be isolated from ground.
    See the warning at the bottom of Page 9 of the MA34000 data.

    I think you would have to use something like an opto isolator or solid state relay with a *very* low 'coil' current, that would work using the Pot 5V supply as a power source, so the whole circuit is isolated.