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one FB produce two Events, but only one outputValue, Does 4DIAC result meet the 61499 [message #1849681]

Sat, 29 January 2022 04:03

Eclipse User

I'm doing an experiment, one FB run two times, and produce two different events, however, two events give two different values in one data output,
Then, two different FB receive each event and same data output, then check the data they get.
I build a logic by IDE, the pic is attached, after E_CYCLE_2 send output EO, E_CYCLE_1 and E_CYCLE_3 executed, E_CYCLE_1 send output EO and E_CTUD CU receive, E_CYCLE_3 send output EO and E_CTUD R reveive.
Then, E_CTUD executed two times, first time running with R event , then RO event produced and CV data value = 0, next time running with CU event, then CO event produced and CV data value = 1,
Next, E_DEMUX receive CO event, E_DEMUX_2 receive RO event, they all copy CV value to K,
E_DEMUX get CO event and K = 1, that's right, but E_DEMUX_2 get RO event, k=1, K is not the value when E_CTUD produced RO event.
Is this result follow 61499 standard?When FB execute input Event, shouldn't the input data be equal to the data generated when this event is executed?

Attachment: testLogic.png
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Attachment: testlog.PNG
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Re: one FB produce two Events, but only one outputValue, Does 4DIAC result meet the 61499 [message #1849683 is a reply to message #1849681]

Sat, 29 January 2022 07:11

Eclipse User

Hi,

this is an interesting experiment. IEC 61499 is not explicitly clear about how such situation should be handled. I think the definitions in the standard a roughly like when an output is sent the associated data outputs shall be made available to the outside of the FB and when an input event is received the associated data inputs shall be updated. Also the standard says that this can but must not be something equivalent to sampling inputs. So the standard leaves here room for interpretations and different implementations. In 4diac FORTE we decided that we are having a buffer of size one on all data connections. On sending output events the FB outputs are copied to this buffer on reception we are sampling from the connections. Which fulfills the definition of the standard and also gives a nice upper bound on the required memory. But we are happy for any suggestions, either for 4diac FORTE or also for IEC 61499 itself.

PS: Please note that your E_CYCLE_2 has no functionality. An E_CYCLE should ignore any START events if it is currently running.

Re: one FB produce two Events, but only one outputValue, Does 4DIAC result meet the 61499 [message #1849693 is a reply to message #1849683]

Sat, 29 January 2022 20:47

Eclipse User

Hi
We check 61499 standard about event and data relationShips, pls see my pic, so we think the input data be equal to the data generated when this event is executed.
But where does the standard says that this can but must not be something equivalent to sampling inputs, can you also please point out where the doc indicated and attach the doc for us? Maybe we didn't look carefully enough, It's best to document this principle

Thanks

Attachment: 61499.png
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Re: one FB produce two Events, but only one outputValue, Does 4DIAC result meet the 61499 [message #1849699 is a reply to message #1849693]

Sun, 30 January 2022 05:31

Eclipse User

Hi,

can please remove the picture. You can not post screenshots of a standard here!

The text you pointed out is about that input data has to be consistent when the FB itself is executed. This is a general theme. I checked several parts of the standard and it seems to be scattered around and rather vague. you might consider the clauses: 4.5.3, 5.2.1.2, and 5.2.2.4 and for the latter especially Table 1.

I hope this helps. One of my current tasks for the standard is to improve the whole clause 4 so I'm happy for any feedback.

alois

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