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Thread: Dual HMIs

  1. #1
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    Dual HMIs

    Customer with a group of motors that they would like to control at two locations. I have never done it so am wondering if I can network 2 HMIs with 1 PLC. If so, what might be some of the things to avoid?
    Tom
    TBLO

  2. #2
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    Quote Originally Posted by ptonsparky View Post
    Customer with a group of motors that they would like to control at two locations. I have never done it so am wondering if I can network 2 HMIs with 1 PLC. If so, what might be some of the things to avoid?
    Yes, what you need is an HMI system that supports what is called a "Thin Client" application. One HMI is the primary, it communicates (usually via ethernet) to the PLC and to the second "thin client" HMI. The 2nd HMI is showing the exact same OI as the primary and in most of them, you can enable or disable functionality at that 2nd location. An example would be to allow someone to view anything, or stop anything, but not start anything other than at the primary. The Thin Client issue allows the use of a less expensive version of the HMI hardware since it is not running the entire HMI application software.

    There are other ways of doing it, many are dependent on what you are using as a network.

  3. #3
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    What Jraef is talking about is a PC based HMI, like Wonderware Intouch or RSView32. These are usually higher dollar and great for more complicated and integrated systems.

    There are also simpler panelview products, which are just HMI software usually running on windows CE, like AB Panelview Plus. There are hundreds of manufacturers of CE based HMI products, and some cheaper then AB. For all of them you can just put the same application in both HMIs and point them both at the same PLC. Ethernet is usually preferred for communications.

    Good Luck, Steve

    AB Panelview Plus:
    http://www.ab.com/en/epub/catalogs/1...482/index.html

  4. #4
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    I just thought, U could just, Google some images or be a reader... here (Electro)

    ... :grin: Enjoy
    If your even thirsty, your two quarts low.

  5. #5
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    Yes, in the past I have had 6 HMI's connected to one plc.

    You could use RedLion G3 series. As Steve points out, your plc needs to support multiple connections and Ethernet would be very good. If your plc has only have one serial port, then you'll need a multiplexer device to allow this.

    You may want to post your particulars (distance, plc type, # of items to display) over at http://www.plctalk.net/qanda/forumdisplay.php?f=2 for more exposure.

  6. #6
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    Quote Originally Posted by ptonsparky View Post
    Customer with a group of motors that they would like to control at two locations. I have never done it so am wondering if I can network 2 HMIs with 1 PLC. If so, what might be some of the things to avoid?
    most HMI/PLC systems can do this, often just by duplicating the HMI. I do this pretty regularly. it is pretty straightforward.

    if your PLC does not have a network capable port, your solution will be much harder. most PLCs these days support some kind of networking though.

    if you can post what brand/model of plc you are using, it will be fairly easy to tell you how to accomplish what you want to do.
    Bob

  7. #7
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    As others have said, this is a straightforward application for a PLC. My experience is with Allen Bradley ControlLogix series. You can have as many HMIs as you can afford. Have them operate on 10/100 ethernet and you can even use redundant switches if you want. You can even get Cisco industrial swtiches from A-B. Use the PanelView HMI and program them identical to simplify. This may not be the cheapest solution, but is easy to maintain and keeps spare parts down.

    TxEngr

  8. #8
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    Haven't started the project yet. I have to design it and sell it first. That means setting up a working model in my shop first. I use have used AB plcs and HMIs because that is all we have in this area for local support. RS500 and PanelBuilder 32. I also have software for both HMIs & PLC from automation direct. Haven't more than installed the software for those yet.
    Tom
    TBLO

  9. #9
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    Multiple HMI

    Sure no problem.

    My suggestions:

    A. Never used maintained pushbuttons on the HMI
    B. The use of Momentary pushbuttons on the HMI is prefered, use subsequent logic in the PLC for on/off, or push-on/push off control.
    C. The PLC is the MASTER
    D. Don't have the seperate HMI's trying to modify the same address (tag)
    E. Each HMI should modify a UNIQUE bit address (tag) in the PLC
    F. Write the rung in the PLC so that there are branches such as:
    HMI1 Start PB
    HMI2 Start PB
    HMI1 Stop PB
    HMI2 Stop PB

  10. #10
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    Quote Originally Posted by IMM_Doctor View Post
    A. Never used maintained pushbuttons on the HMI
    There are purposes for maintained push buttons. You would use one to toggle a configuration bit.

    Quote Originally Posted by IMM_Doctor View Post
    D. Don't have the seperate HMI's trying to modify the same address (tag)
    E. Each HMI should modify a UNIQUE bit address (tag) in the PLC
    I would never recommend this. You are creating a headache for yourself, when it gives you 0 added benefits.

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