System Start-up Behaviour

Initial Operation

The ETHERCAT protocol is handled by the ETHERCAT Communication Module and the PLC operating system automatically. When the Communication Module is initiated in the proper way and the user application is running, the Communication Module and the bus become active.

No function blocks are necessary for exchanging process data via ETHERCAT. Furthermore, it is possible to access the send data and the receive data in the according operands range directly. The access takes place with either operand or symbolic variables. Special ETHERCAT functions can be realized by using the function blocks of the ETHERCAT library.

To include an AC500 ETHERCAT Communication Module in the PLC system, create an ETHERCAT configuration and write it into the Communication Module. A detailed documentation can be found in the document “Example: ETHERCAT Configuration”.

System Start-up

When the user application changes in the run mode, the Communication Module tries to establish communication with the configured slaves.

The Communication Module will not change in run mode if:

  • the number of the configured slaves is not equal to the number of connected slaves.
  • the type of the configured slaves is not equal to the type of connected slaves.

In this case, the LED STA2 ETHCAT (Master Communication Module) switches on.

After communication to the slaves is established, the distributed clocks will be synchronized. This process can last up to 1 minute. During the synchronizing process, the LED S-ERR (slave) switches on. After a successful synchronization of the distributed clocks, the LED S-ERR switches off and the LED PWR, STA1 ETHCAT and STA2 ETHCAT of the slave are on.

For details see the device description of CM579_ETHCAT: CM579-EtherCAT - EtherCAT® MasterCI511: EtherCATâ Bus Module CI511-ETHCATCI512: EtherCATâ Bus Module CI512-ETHCAT

Note

If a bus module will be disconnected from the ETHERCAT network during operation, it will not continue with the communication after re-connecting. A restart of the whole system must be performed.