Annex B (informative) Use cases ToC Previous

B.4 Get list of available device parameters ToC Previous Next

B.4.1 Use case: Browse device parameters ToC Previous Next

Use Case Browse device parameters.  
Description    OPC Client has the UI windows for displaying the device details information.   If the device has the blocks, the UI window displays block names which the device has.   If a device has blocks, the UI window displays parameter names which are included in blocks.If a device does not have a block, the UI window displays parameter names which the device has.  
Stakeholder Mass Configuration  
Preconditions Use Case B.2 (List Topology)  
     
Post conditions On the OPC client, user can see the parameter names which the device or the block has.  
Actors Engineer, Expert, Observer, Plant Asset Manager  
Trigger Whenever a user needs a list of parameters for further access.  
Frequency    
Description    
  Step Action
  1 On OPC Client, user opens a UI window of a device which is selected on the topology which is listed by the Use Case B.2.
     
  2 User browses a name list on the selected device in the OPC Client.
  3 OPC Server retrieves a name list of the selected device.
  4    OPC Client displays a name list to user.If selected device has blocks (if the device is FF-H1 or PROFIBUS PA), OPC Client displays the block name list.
  5 User selects an item in the name list, and user browses the selected item (block name list or parameter list).
  6 If the object type of selected item is “Block”, OPC Server retrieves available parameters of the selected block.
Extension    
  Step Branching Action
  4 OPC Server gets the attributes (Label Name / Help Description) of the selected item in the list and displays in the OPC Client.
Variations    
  Step Branching Action
  4 If selected device has no blocks (if the device is HART), OPC Client displays the parameter name list.
  6    If the object type of selected item is “Parameter”, OPC Server retrieves available attributes of the selected parameter.For the enumeration case, an OPC Client displays the corresponding label with the value.
Exceptions Step 2, The device is not ready to communicate.  
  Step 3, The DTM which is browsed does not provide a block list (if the device is FF-H1) or a parameter list.  
  Step 6, If the object type of selected item is “Parameter Element”, OPC Server does not return a list. OPC Client displays a message informing user that there are no available items.  
Requirements User has access permissions to the server  
Notes    [Hierarchy of items]   [Up to the parameter]   FF-H1 / PROFIBUS PA : {Device} — {Block} — {Parameter}    HART : {Device} — {Parameter}   [Up to the element]   FF-H1 : {Device} — {Block} — {Parameter} — {Element(*)}         (*) Element = the member variable of the structure   [Up to the enumeration]   FF-H1 / PROFIBUS PA : {Device} — {Block} — {Parameter} — {Enumeration}   FF-H1 : {Device} — {Block} — {Parameter} — {Element} — {Enumeration}HART : {Device} — {Parameter} — {Enumeration}  
Open Issues    

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