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Thread: Sending command with IEC850 and communication error

  1. #1
    nmblanquart Gast

    Default Sending command with IEC850 and communication error

    Hello,

    I am currently working on both ZenOn 6.51 and 7.00 versions, and I noticed a strange behavior that can be problematic while using the control/command function.

    When the communication is down (I-BIT or "Runtime Timeout" is set), and a command is sent to the equiment, nothing appear. But, when the communication comes back, the command is sent, and it can be dangerous to the people working near this equipment.

    Is there any solution to avoid sending this command when the communication is down?

    Thanks for your answers.

  2. #2
    Join Date
    30.05.2007
    Location
    Salzburg
    Posts
    880

    Default AW: Sending command with IEC850 and communication error

    Is there any solution to avoid sending this command when the communication is down?
    When the communication is down, a set command will also not be able to pass a broken connection.
    The feedback variables will always show the correct status of the communication to the device (SPONT, INVALID, ... )
    The command variables usually are not shown i.e. in dynamic elements - instead commands are set via the command screen.

  3. #3
    Join Date
    01.07.2008
    Location
    Salzburg, AT
    Posts
    870

    Default Re: Sending command with IEC850 and communication error

    The general rule in zenon is that when a driver detects the connection loss to the PLC it sets INVALID status bit (I-bit) to all variables and it empts its internal queue with all "pokes" currently waiting yet to be written to the PLC. But when during connection loss - after you've got I-bits - you write some next value, then it will be placed in the queue and after reconnection - will be sent to the PLC.

    Please change your project: lock - e.g. using Interlocking - the possibility to use commands during connection break.

    To detect the connection loss in IEC61850 protocol at least one variable (DataAttribute) must be always polled - not in a Report. And this variable must be advised all the time, e.g. it will be advised all the time when you link this variable with a reaction matrix making alarm "connection loss" in reaction on I-bit. This alarm can also activate an Interlocking used by all commands entries in your project.

    According the Standard each IEC61850 server must have in LLN0 the DataObject Mod (of common data class INC) which have some mandatory DataAttributes: stVal, q, t, and ctlModel. As it does not make really sense to report this DataObject, you can probably use LLN0/Mod/stVal[ST] for connection loss detection. Or, by server "officious" using reporting - for all they have - you can take LLN0/Mod/ctlModel[CF] - the functional constrain CF cannot be reported at all (only ST and MX data can be reported).

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