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davidepalombo
 Â· Posted in SDK

ctrlx SDK Realtime C

Hello everybody,

Our customer is planning to migrate their real-time code from an industrial PC to the ctrlX platform. The code is written in C and consists of a series of services managed by a task manager.

In the Real-Time SDK, I only find examples related to C++. Is it possible to use C, particularly to interface with the ctrlX scheduler?

Thank you in advance!

4 replies
nickH

Hi,

Davide is right with what he has discovered: Its possible to develop and run Bundles in C at Apache Celix. We don't have samples in C in the RT-SDK. But you can have a look at the examples from apache celix on github. But then there is also the problem, that we don’t have a service for the scheduler in C at the moment.

I talked to the developers of the ctrlX Scheduler. They told me, that they first planed to do a C-service for the scheduler, but removed this from the backlog, because no one has ever asked for a C-service before. I can also ask the Data Layer developers, but I guess it might be the same reason. If there is a demand to do that feel free to contact me.

Best regards,

Nick

Sgilk

davidepalombo ,

I don't believe we support C Celix bundles at this time. nickH , please correct me if I'm wrong here.

Why would there need to be a heavy refactoring of the C services to wrap them in C++ bundles? I would think you could use them as is.

d

Hi Sgilk, 

thank you for your reply. I'll be a bit more specific:

I already have access to the realtime SDK. I read the documentation so I know the realtime system of the ctrlX utilizes Apache Celix. In particular the Celix framework support building bundles written in C (e.g. celix/examples/celix-examples/hello_world_c at master · apache/celix).

My first idea was to build a Celix bundle directly written in C, but looking at the examples provided in the rt-SDK, they use external C++ files, in particular:

  • "common/scheduler/i_scheduler3.h" for register the callable in the scheduler
  • "comm/datalayer/datalayer.h" for interacting with the datalayer-rt

While with the non-realtime SDK there are C interfaces for accessing the datalayer, in this case I was not able to find any C interfaces related to these two header files.
It means that, if a build a C Celix bundle, it will not be able to interact with the scheduler and the datalayer-rt.
Is it correct, or am I missing something?

I understand that I could put my C code wrapped inside the C++ bundles, but that would mean a heavy refactoring of the code, since it is composed by tens of services and millions of lines of code.
 
Thanks!

 

Sgilk

Hi davidepalombo ,

The realtime system of ctrlX OS utilizes the Apache Celix framework. You can absolutely run services written in C, but there will be some C++ required to build as a Celix bundle. There is an example in the realtime SDK (samples-cpp/plc-c-interface) which creates a Celix bundle containing services written in both C and C++.

To access the realtime SDK, a training is generally required. See this article.

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