Defining, viewing, and controlling data mappings

Overview

Data mappings can be defined, deleted, viewed, and have their state controlled.

The Data Mapping feature provides the function to:

• Read a source device variable at a defined frequency
• If the device variable has changed since the last read, write it to a destination device variable
• Optionally, include transformation from one data type at the source device variable to a different data type for the destination device variable.

Data mappings are defined on the node where the source device driver and destination device driver are installed and where the device specific communication to the physical devices will take place. Physical devices types include: PLCs, controllers, sensors, and bar code readers.

In the case of logical devices, the device is defined on the node where the memory representation of the device and its variables will take place. There is no physical device to connect to and no communication protocol to support. Logical device types include: global variable device, aliases device, and property file reader device.

Once a data mapping is defined and Started, the runtime handles the reading of the source device variable, processing, and the writing of the destination device variable.
There is no need for a separate trigger to be defined to do this device variable access (for example using the Set action).

The Data Mapping feature can be used to compliment, and be a part of, the M2M solution application logic that users define in triggers.

Defining data mappings

Data mappings are defined after the devices referenced for the source device variable and destination device variable are defined and Started.
Follow these steps to add a data mapping definition to a node:

1. From the left pane, expand the node that you want to add a data mapping definition to.
   
2. Select the Devices icon.
   Then select the Data Mapping tab
   Or, alternatively, select the Data Mapping sub icon.
   
   The Data Mapping window appears as the right pane.
   For this example, the Data Mapping window has previously defined data mappings.
   
   
3. From the bottom of the Data Mapping tab, select New.
   A new Data Mapping window appears.
   
   
4. Select a value for the Priority (ms) parameter.
   This is the frequency that the runtime Device Publisher feature will read the source device variable.
   The units are in milliseconds (ms).
   
5. Select a Source Variable.
   The list of devices are the Started devices on this node.
   Expand the desired device and its internal structure until you can select the individual source device variable.
   
6. Select a Destination Variable.
   The list of devices are the Started devices on this node.
   Expand the desired device and its internal structure until you can select the individual destination device variable.
   
7. If the drivers support data transformation, the data type fields will become active and can be changed to a data type different than the variables' data type.
   
8. If the source device variable and the destination device variables are arrays, enter the Count of variables to transfer.
   
9. Use the Save button to save the definition of the data mapping.
   The data mapping will appear in the list of data mappings for the node, in a Stopped state.
   

Viewing data mappings

The Data Mapping tab provides a list of data mappings defined on the node.

To use the Data Mapping tab, follow these steps:

1. From Workbench left pane, expand the node whose data mapping you want to view.
   
2. Select the Devices icon.
   Then select the Data Mapping tab
   Or, alternatively, select the Data Mapping sub icon.
   
3. The Data Mapping tab provides a table format that lists the data mappings defined on the node.
   The top section of the Data mapping tab provides these columns:
   

   Column	Description
   Priority	The priority of the data mapping, specified in the millisecond frequency that the runtime Device Publisher will read the source device variable.
   Source	The source device variable.
   Destination	The destination device variable.
   State	The data mapping state, which can be: Started - the data mapping is active. The runtime Device Publisher is reading the source device variable at the priority frequency. Stopped - the data mapping is not active. Disabled - indicating there is a problem communicating with the source device.
   Last Executed	Date and time when the data mapping was last executed, including the write to the destination device variable.
   Successes	The number of successful data mappings from the source device variable to the destination device variable.
   Failures	The number of failed data mapping. This is usually caused by the destination device not being in a Started state.
   Overflow	The number of times the runtime Device Publisher cannot process the data mapping in a timely manner. The entire node's definitions of data triggers, variable groups and data mappings defines the load on the runtime Device Publisher. Each of the Priority parameter values defines the list of device variables that need to read and processed that the Priority's millisecond frequency. You might want to change the value set in the Priority parameter.

   
   

Data Mapping status information

The bottom portion of the Data Mapping pane provide information concerning the performance of the selected data mapping as follows:

Controlling data mappings

When a data mapping row is selected in the table, the buttons at the bottom of the Data Mapping tab become enabled or disabled. This is based on the current state of the data mapping and the function of the button.

A single data mapping row or multiple data mapping rows can be selected and then the function buttons used, but the state of each data mapping will determine if the function can be performed.

A data mapping row's pop-up menu can be displayed, and the available options selected.