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

Use Case

Get attributes of a device parameter

Description

OPC Client has the UI windows for displaying the device details information.

The UI window displays parameter names, its’ engineering units and values (if the parameter is readable).

When OPC Client displays the value of a parameter, the value is displayed according to the “display format“, which is described in the DD.

If the OPC Client also has the parameter-write-function and if the parameter is writable, an UI-element for writing the value to a parameter is displayed.

Stakeholder

Mass Configuration

Preconditions

Topology and device node are available in OPC UA Server

Device is connected to the OPC UA Server.

OPC Client gets the parameter list of a device from OPC Server.

To display the parameter name and its value, OPC Client tries to get the detail information of each parameter.

Post conditions

On the OPC client, user can see the parameter names, and can see the detail information for each parameter.

Detail Information of parameter:

the data type, the label name, the minimum value, the maximum value, the engineering units, writable, readable, the enumeration list, the display format, the edit format.

Actors

Engineer, Expert, Observer, Plant Asset Manager

Trigger

Whenever a user needs the attributes of parameters for further access.

Frequency

Description

Step

Action

1

OPC Client requests to get the attributes of a parameter of a device to OPC Server.

2

OPC Server gets the attributes of the parameter which is specified by OPC Client from the device DTM.

3

OPC Client displays the parameter name to use the label name, and the engineering units.

Exceptions

Step 1, The specified parameter does not exist in the device.

Requirements

Notes

To use the attributes of a device parameter which is gotten by this use case, OPC Client can work as follows.

[For read parameter]

OPC Client can recognize a parameter is readable or not, and then OPC Client gets the value of the parameter via OPC Server from the device.

OPC Client displays the corresponding label with the value if the data type of a parameter is the enumeration, otherwise (if the data type is not the enumeration) OPC Client displays the value according to the “display format“.

[For write parameter]

OPC Client can recognize a parameter is writable or not, and then OPC Client can check the entered value whether the data type, and the minimum value and the maximum value of the entered value are correct or not when user tries to write a value to a parameter.

Open Issues