Defining the PDO Mapping

This topic contains the following sections:

General information on Process Data Objects (PDO)

Click here to obtain basic information on PDOs

Working with PDOs in PLCnext Engineer

In PLCnext Engineer, the PDO mapping of a slave is implemented in the 'PDO Data' editor. By default, the editor lists the PDOs specified in the ESI file. A detailed editor description can be found in the topic "'PDO Data' Editor (EtherCAT Slave Device)".

To open this editor, double-click the slave to be configured in the PLANT. Then click 'PDO Data' in the editor area on the right.

In the 'PDO Data' editor you can perform the following operations:

Integrating a PDO into EtherCAT data frame and Data List

By marking the checkbox in the 'Active' column of a PDO, it is embedded into the EtherCAT data frame and is available in the Data List of the slave. There, each process data item can be assigned to a variable to be further processed in the application.
By deselecting the checkbox in the 'Active' column of a PDO, it is not used in the EtherCAT data frame and hidden in the Data List.

Some basic and required PDOs may be activated by default and cannot be deactivated.

Modifying existing PDOs

Note
Note that the following operation is only possible if it is allowed by the slave.

Open the PDO to be edited in the list. For that purpose left-click into the respective table row header ('Inputs' or 'Outputs' table) and click the icon on the editor toolbar.
The 'Edit PDO Data' dialog box appears. The 'Entries' list in the lower half of the dialog box shows the objects which are currently members of the PDO.
Deleting an object from the PDO:
1. Select the object to be removed in the 'Entries' list and click the icon on the editor toolbar.
2. Click the 'Apply' button.
3. Repeat the steps a. and b. for each object to be deleted.
4. Proceed with step 3. to add other objects to the PDO.
  To complete the editing and close the dialog box, click 'OK'.

Adding an object to the PDO:

On the editor toolbar, click the . The tab 'PDO Entry' is opened.

In the section 'CoE object dictionary' (in the lower half of the editor), the available objects of the slave are listed.

Select the object to be added.
Click the 'Apply' button.
Add further objects by repeating steps a and b.

Alternatively you can specify the object to be added by filling in the fields in the sections 'General' and 'Settings'.

Click here for a description of the fields on the 'General' tab

Click here for a description of the fields on the 'PDO Entry' tab

Open the 'General' tab again.
In the grid under 'Entries', the previously selected objects are listed.
Click 'Ok' to close the 'Edit PDO Data' dialog box.

Section	Element	Description
General	Name	Name of the object to be added to the PDO.
Comment	You can add a user-defined descriptive comment.
Index Subindex	The index and subindex uniquely identifies the object in the Object Dictionary of the slave. Note that the editor distinguishes between a decimal and hexadecimal entry (selectable by the button on the right of the input field).
BitLength	Length of the object in bits.
Settings	Type	Data Type of the object.
Swap	Keep either 'None' (to keep high and low bytes of the entry in their regular order) or select 'Swap high and low bytes'.
Show Base Data Types	Defines which data types are listed in and can be connected from the 'Type' drop-down list (see above). If activated, only EtherCAT base data types are listed in the 'Type' drop-down list. If deactivated, the user-defined data types from the ESI files are listed in the 'Type' drop-down list.
CoE object dictionary		Shows the Object Dictionary of the slave. By selecting an entry, its values are loaded into the editor fields in the sections 'General' and 'Settings'. Click here for a description of the search function The search operates on all visible texts in the shown Object Dictionary. Enter the search text into the 'Search' input field at the top right in the area. The search is directly applied when entering the text. All strings that match the entered text are highlighted. To deactivate the search, i.e., to delete the search string entered, click the delete icon on the right of the 'Search' input field.

Adding user-defined PDOs

Note

Note that the following operation is only possible if it is allowed by the slave.

Depending on the slave type, it may be necessary to delete a predefined PDO from the list before inserting a user-defined PDO (because the slave cannot manage more than the existing PDOs, for example). Information on this can be found in the technical manual of the slave device.

Delete an existing PDO from the list if this is required by the current slave. For that purpose left-click into the respective table row header and click the icon on the editor toolbar.
Click the icon on the editor toolbar to open the 'Add PDO Data' dialog box.

In the dialog box, fill in or select the field entries on the 'General' tab:

Section Element Description

General Name User-defined name of the PDO.

Index Unique index of the PDO in the CoE Object Dictionary.

Note
Make sure that the index you are defining is available and free in the Object Dictionary of the slave.

After selecting the 'Direction' of the new PDO (see next row), the system automatically proposes the first free index.

Direction Defines the data transfer direction of the PDO:

RxPDO: Write data to slave

TxPDO: Read data from slave

Entries In this tabular view, the already added objects are listed with their 'Name', 'Index', BitLength' and a user-defined comment (if available).

Exclude Select existing PDOs which are excluded if this PDO is active. That means, the state of an excluded PDO cannot be changed.

Flags Mandatory If set, the PDO is marked as mandatory in the ESI file.
This flag is read-only and cannot be changed for new PDOs. Instead, it is configured in the ESI file.

Fixed Context If set, no additional entries can be added to the PDO.
This flag is read-only and cannot be changed for existing or new PDOs. Instead, it is configured in the ESI file.

Virtual PDO PDO's which do not have entries are marked as virtual.

Open the tab 'PDO Entry' of the 'Add PDO Data' dialog box.

In the section 'CoE object dictionary' (in the lower half of the editor), the available objects of the slave are listed.

Select the object to be added.
Click the 'Apply' button
Add further objects by repeating steps a and b.

Alternatively you can specify the object to be added by filling in the fields in the sections 'General' and 'Settings'.

Click here for a description of the fields on the 'PDO Entry' tab

Open the 'General' tab again.
In the grid under 'Entries', the previously selected objects are listed.
Click 'Apply' to confirm the object population of the PDO.
Then click 'Ok' to close the 'Add PDO Data' dialog box.

Section	Element	Description
General	Name	Name of the object to be added to the PDO.
Comment	You can add a user-defined descriptive comment.
Index Subindex	The index and subindex uniquely identifies the object in the Object Dictionary of the slave. Note that the editor distinguishes between a decimal and hexadecimal entry (selectable by the button on the right of the input field).
BitLength	Length of the object in bits.
Settings	Type	Data Type of the object.
Swap	Keep either 'None' (to keep high and low bytes of the entry in their regular order) or select 'Swap high and low bytes'.
Show Base Data Types	Defines which data types are listed in and can be connected from the 'Type' drop-down list (see above). If activated, only EtherCAT base data types are listed in the 'Type' drop-down list. If deactivated, the user-defined data types from the ESI files are listed in the 'Type' drop-down list.
CoE object dictionary		Shows the Object Dictionary of the slave. By selecting an entry, its values are loaded into the editor fields in the sections 'General' and 'Settings'. Click here for a description of the search function The search operates on all visible texts in the shown Object Dictionary. Enter the search text into the 'Search' input field at the top right in the area. The search is directly applied when entering the text. All strings that match the entered text are highlighted. To deactivate the search, i.e., to delete the search string entered, click the delete icon on the right of the 'Search' input field.

The new PDO is now listed in one of the tables 'Inputs' or 'Outputs' (depending on the 'Direction' you have selected in the 'Add PDO Data' dialog).