Hello, everyone!
I am currently working on implementing an openPOWERLINK network. However, the amount of data I would like to send to each CN within a single cycle is much greater than the maximum frame size. So my question is: are you planning to introduce the Multiple Preq/Pres extension into the public stack? If not, what solution would you suggest for my problem?
Ivan
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Do you mean that each CN receives more than 1492 bytes every cycle i.e. as critical data or is it non-critical data which can be sent in async/sdo ?
What is your target network cycle time and how many CNs need this kind of data exchange ?
The public stack development has been static for quite some time now.
But depending on your exact use-case, there may be another way e.g. either SDO or using Pres chaining with Preq/Pres.
Best,
John
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Each CN receives (and sends, sorry for not bringing it up in the original post) > 1492 bytes of critical data, so it's not an SDO case.
My current cycle time is 30 ms with Linux userspace MN and two STM32 boards as CNs (1492b Preq/pres frames). It's difficult to talk about the target cycle time right now, as this is an early stage of the project. As for the number of CNs that may require this kind of data exchange, ideally, I would like all 239 CNs to support it.
Ivan.
Last edit: Ivan 2025-10-03
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Okay, so in that case, the existing options of using Pres chaining also would not fit for your target data rate, and as you have mentioned sdo would not work for cyclic data exchange. Considering your tentative target numbers, there are a few possible options; will share with you to consider.
-John
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Hello, everyone!
I am currently working on implementing an openPOWERLINK network. However, the amount of data I would like to send to each CN within a single cycle is much greater than the maximum frame size. So my question is: are you planning to introduce the Multiple Preq/Pres extension into the public stack? If not, what solution would you suggest for my problem?
Ivan
Hi Ivan,
Do you mean that each CN receives more than 1492 bytes every cycle i.e. as critical data or is it non-critical data which can be sent in async/sdo ?
What is your target network cycle time and how many CNs need this kind of data exchange ?
The public stack development has been static for quite some time now.
But depending on your exact use-case, there may be another way e.g. either SDO or using Pres chaining with Preq/Pres.
Best,
John
Thanks for the quick response!
Each CN receives (and sends, sorry for not bringing it up in the original post) > 1492 bytes of critical data, so it's not an SDO case.
My current cycle time is 30 ms with Linux userspace MN and two STM32 boards as CNs (1492b Preq/pres frames). It's difficult to talk about the target cycle time right now, as this is an early stage of the project. As for the number of CNs that may require this kind of data exchange, ideally, I would like all 239 CNs to support it.
Ivan.
Last edit: Ivan 2025-10-03
Okay, so in that case, the existing options of using Pres chaining also would not fit for your target data rate, and as you have mentioned sdo would not work for cyclic data exchange. Considering your tentative target numbers, there are a few possible options; will share with you to consider.
-John