Configuration of More than 4 PDOs per Node

At a Glance

For each node, 4 transmission PDOs and 4 reception PDOs can be configured. This is because the Sycon software automatically generates the COB-IDs to guarantee their unicity and uses an algorithm respecting profile 301. The following paragraph explains this operation.

To be able to use more than 4 PDOs in each direction, you must use a manual procedure like the one described for creating a 5 th PDO.

How the COB-IDs are Assigned

Possible COB-IDs are between the values of 385 and 1407 (16#180 and 16#57F).

You can use the COB-ID of your choice for each PDO; however, the COB-IDs must be unique in this interval of values. The CANopen configuration tools such as Sycon are configured by default to provide a COB-ID that respects these constraints.

The following table describes the algorithm used by the Sycon software to carry out these COB-ID assignments.

PDO	ID	Node 1 (decimal)	Node 2 (decimal)	...	Node 127 (decimal)
1.TXPDO	16#180+ID-Node	385	386	...	511
1.RXPDO	16#200+ID-Node	513	514	...	639
2.TXPDO	16#280+ID-Node	641	642	...	767
2.RXPDO	16#300+ID-Node	769	770	...	895
3.TXPDO	16#380+ID-Node	897	898	...	1023
3.RXPDO	16#400+ID-Node	1025	1026	...	1151
4.TXPDO	16#480+ID-Node	1153	1154	...	1279
4.RXPDO	16#500+ID-Node	1281	1282	...	1407

As the COB-ID determines the priority of the message (the weaker its value, the greater its priority), the consequences are the following:

The first PDO in the node has greater priority than the second, third and fourth.
A transmission PDO has priority over a reception PDO in the same node.
The lower the node number, the greater the priority of the node's PDOs.

How to Create a Number 5 PDO

The table below describes how to create a 5th PDO for a given node.

Step	Action
1	Configure a PDO5 from the node configuration screen. Result: a warning window appears to indicate that it is not possible to create a new PDO. This is normal, given what was said previously (a maximum of 4 PDOs per node).
2	In the node configuration screen, disable the Auto COB-ID option. Result: you can now write a new COB-ID for the PDOs that you want to create and thus define the new priorities in the messages transmitted on the CANopen bus. Caution: you must respect the unicity of the COB-IDs. The numbers available are: TXPDO: 1664 to 1759, RXPDO: 1761 to 1792.
3	Close the node configuration window and save your project.