high and low update rate

[tuxembedded]

Good morning!

We try to get two different slave groups working: (1) 20 Bytes process image and 10kHz update rate (2) 1kByte process image and 100-1000Hz update rate We managed to get (1) and (2) working, but isolated from each other: when using (1) the other group (2) isn't connected to EtherCAT.

But if we start using two different groups with different update rates, like explained here:

EtherCAT slave groups

Slave groups can be used to group slaves into separate logic groups within an EtherCAT network. Each group will have its own logic address space mapped to an IOmap address and make it possible to send and receive process data at different update rate.

We only get 4,4kHz for (1) and 3,2kHz for (2). What did we try:

• change the order how the slaves are connected to the bus so that the fast slaves are directly connected with the master. No effort.
• use only one group "1" for (1) and use group "0" for both (1) and (2). No effort. For us it seems that when exchanging data with (1) there is also 1kB+20Byte process data exchanged which is too much for the machine. We only want to exchange 20 Bytes process data when doing the (1) cycle. Is this possible?

This one says (in table below Process Data Exchange): Having different cycle tasks (multiple update rates for PDO) isn't possible with SOEM ...

Any hint would be very helpful.

Thank you very much!

Daniel