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accessing the process image

Posted: 13 Mar 2017, 18:02
by wglatz
Dear RevPi Team,

do you supply any form of documentation for the process image and possible interfaces?
I already know from your tutorials how to access it with a C-API but am in need for a proper documentation.

Greetings,
Wolfgang

Re: accessing the process image

Posted: 13 Mar 2017, 23:08
by volker
The code is is the best documentation you can get. There are just these few calls noting else. Which specific questions would you like to be answered? Please also view the Pyton code I've provided for Vieo Tutorial 16 and the according download under Support ("Code Beispiel aus Video Tutorial Nr. 16").

Re: accessing the process image

Posted: 30 May 2017, 10:09
by chrisinfranet
..."just do it"....
means in this case, for each procees Image one needs a new acces library compilation in C ?
For accessing from Java, it has to be done through a xxxx.SO compilation each new Image (?)

Or is there a dynamic scheme supported? If yes, out of C only or for Java too?

I am new here ...and may have missed tons of Information.

- Chris -

Re: accessing the process image

Posted: 31 May 2017, 13:17
by volker
Hi Chris,
our emphasis for KUNBUS developed software was EN61131 control systems. Logi.RTS does have an import mechanism of the PiCtory data structure.
If you want to make your software flexible please use the following hints:
1) Use symbolic names instead of absolute process image offsets. in case of a restructuration of your system you just need to add the new symbols to your code.
2) Use the JSON file generated by PiCtory and a JSON parser to extract the information and to use it in you code. this way you can be absolutly flexible.
3) have a look on the demo code of Dirks alarm clock (part of Jessie image which will be online tomorrow). he uses a call of piTest -d and parses the system response in order to get device offsets of the current configuration. This is another way to make your code more flexible.

members of the community have already programmed wrapper code to make access to the process image more easy and flexible. This is what a community project is all about. Please don't expect "Don't just claim it, make it" to mean that you get all kind of thinkable solutions ready for copy and paste. It's more meant as an encouragement to the community not to endlessly discuss things but to better start doing stuff. So I would like to encourage you if there is something missing for you to make specific proposals to our community and let us then start programming solutions or even better make them yourself and contribute for all of us...