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You can use the internal interface Manufacturing Data Access to :

  • Read values of manufacturing data points in the PI sheet from another application

  • Write values from the PI sheet to manufacturing data points of another application

  • Subscribe to manufacturing events of another application in the PI sheet

    These events are then automatically reported to the PI sheet as soon as they occur. In this way, you can, for example, subscribe to value changes.

    In addition, events can contain parameters that you can read while processing an event.

All applications that are registered as services at the interface can provide data points and events and receive them from other services. In this way, values from one or more data points can be:

  • Read or written synchronously

    This means on demand (for example, using a pushbutton).

  • Read or written on an event-driven basis

    This means that in running applications, data is automatically read or written – triggered by an event – without the user having to take any action.

Events can also be processed in different system logons running in parallel.

Example Example

User A maintains PI sheet 001. User B maintains PI sheet 002. Value changes in PI sheet 002 can be transferred automatically to PI sheet 001 although the two users are logged on at different terminals.

End of the example.

For more information, see Manufacturing Data Access .


OPC Items and OPC Events

To use data points (items) of the services ODA (OPC Data Access) and OAE (OPC Alarms/Events), you must first have created a subscription in Customizing.

To do so, go to Customizing for Process Management and choose SAP ODA (OPC Data Access) .

For more information about SAP ODA, see SAP OPC Data Access .


Executing Data Access

Data access with MDA can be executed as follows:

  • Manually

    A button with the description saved appears in the PI sheet. The data is not read or written until you have pushed the button.

  • Event-driven

    You can specify an event that triggers data access. The system automatically reads or writes data as soon as the event is triggered.

  • Manual and event-driven

    You can read and write data manually and parallel to this, the data access can be triggered by a defined event. To do this you specify an event.

    Read the value of a data point

If you want to the read the value of a data point, you define it with the type Read and assign it with values using an XStep parameter that you have defined beforehand at the XStep node. The value Read is transferred to the XStep parameter. To display a read value in the PI sheet, define a process instruction of the type Output -> Parameter Value.

Write value to a data point

If you want to transfer a value from a PI sheet as a data point to another application, you define it with the type Write and assign it with a fixed value or an XStep parameter that you have defined beforehand at the XStep node. The fixed value or the value of the XStep parameter is exported as a data point.


  1. You define XStep parameters at the XStep node

    • For all data points that are to be read in the PI sheet

    • For all values from the PI sheet that are to be written to another application as data points

      See also: XStep Parameters

  2. You create an XStep process instruction of type Control Data -> Manufacturing Data Access

    1. On the Data Access tab page, you specify whether the data access should be executed on a manual or event-driven basis or using both these options.

    2. On the Data Points tab page you specify the following:

      • The data points

      • The type of data point (read or write)

      • The value assignment type Parameter or Fixed

      • The XStep parameters to which the data point values should be written

      • The XStep parameters or fixed values to which the data points should be written

  3. To display read values in the PI sheet you create an XStep process instruction of the type Output -> Parameter Value and enter the corresponding XStep parameter.

    See also: XStep: Outputs