Rules for adding a connection to a program parameter

A parameter connection enables data exchange between programs, controller tags, and device tags. Data can be passed into and out of a program during execution. Parameter connections are governed by strict rules regarding data type compatibility, allocation, and connection scope. Rules for parameter connections include:
Data type matching
  • Data types and array dimensions must match exactly.
Usage compatibility
  • Inputs can connect to Output, InOut, or controller/device tags.
  • Outputs can connect to Input, InOut, or controller/device tags.
  • InOuts can connect to Input, Output, or controller/device tags.
  • At least one end must be a program parameter. Connecting two controller/device tags, two local tags, or a local tag to a parameter or controller tag or device tag or routine tag is not allowed.
  • Connecting to routine parameters is allowed.
InOut specific requirements
  • InOut arrays must connect to the whole parameter/tag array, not to members.
  • Value
     is disabled if unconnected or invalid.
    Value
     is enabled and shows tag value when connected. Values cannot be assigned directly to InOuts.
  • Unconnected InOuts in Smart Object instances cause a validation error. Unconnected InOuts in Smart Object instances do not cause validation errors in a Smart Object Definition.
Allocation and connection scope
  • Parameter connections can be established between programs within a Smart Object definition. Parameters cannot connect beyond the root Smart Object definition.
  • Parameter connections must have both ends allocated to the same controller, whether for Smart Object instances, singletons, or controller applications. You must assign device tags to devices on that controller.
  • Connections defined in a Smart Object definition are read-only in instances of the Smart Object.
Multiple connections
  • Output parameters can have multiple connections to the entire tag and any of the members of that tag.
  • Multiple outputs from the same program cannot connect to the same tag.
  • Input parameters can have a single connection to the entire tag or to any of the members of the tag, but not both.
  • An InOut parameter connection must be made to the entire InOut parameter. Tag members cannot have connections.
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