PLCgen test model "empty" does not execute

CIF model: empty.cif

Generated PLC code: MAIN.scl

When running this test, compiling resulted in the error as shown below. As seen, the file size of the program block (OB1) is too small. I'm unsure if this is an issue of the PLC code generator, but this test could not be completed.

Adresses #679

added to epic &3

added CIF TypeBug labels

changed milestone to %v4.0

changed the description

Interesting or sure! I wonder how big it needs to be for it to be OK. Could we make more useful models that also run into this problem?

To solve this, maybe we could add dummy code? If it really is only for an empty models, I'm not sure that's worth it though.

mentioned in issue #679

assigned to @ahofkamp

PLCgen doesn't even create a statement. Technically the generated code is invalid, as it needs at least one statement. (In other words, a ; is missing.)

Not sure why though, iirc it checks for having a statement. Maybe it doesn't know the comment block is not a proper statement? I doubt that ; will create 20 bytes code though :)

Assigning to self, so I can find this again for the missing ; problem.

EDIT: I didn't press "Comment" 6 days ago :p

We can see after adding the ; whether the problem is solved. If not, this can be reopened and we can find alternative solutions.

mentioned in merge request !932 (merged)

mentioned in commit 1a233a7e

Modified PLCgen, please try again.

unassigned @ahofkamp

Running this test from test set v9 with ESCET nightly version 20240623 results in the same error message.

I've tried adding some dummy code lines to increase the file size, but this did not seem to fix the issue. I also noticed that the error message specifically mentions that "the interface" of the standard OB (organization block, i.e. the PLC code) is too small, not the OB itself. I have not yet been able to figure out what this means.

CIF model: empty.cif

Generated PLC code: MAIN.scl

Maybe declare some local variable(s), to see if that helps?

I also found https://support.industry.siemens.com/forum/nl/en/posts/ob-import-issue/308304, which seems to be about the same problem. Maybe that information can help?

We have similar issues with 'The interface of the standard OB is smaller than the minimum value of 20 bytes' also in #890 (closed). It may be the same underlying issue. In #890 (closed) we are progressing towards a potential solution.

changed milestone to %v5.0

I ran some more test for this model. The number of declared variables in VAR_TEMP affects the existence of the error about the interface being smaller than 20 bytes. The minimal example that I was able to create consists of 5 DInt type variables. Remove one of these variables or changing one to a BOOL type results in the aforementioned error.

I have not attempted to determine the number of required BOOL variables to prevent the error message, but I can figure this out (through trial and error) if that is desired.

Example: MAIN.scl

Ah, so it is temp variables. That helps. 5 DINT variables makes sense. DINT is 32-bits, so 4 bytes. 5 * 4 = 20, which satisfies the '20 bytes' requirement.

@ahofkamp I think we can add dummy temp variables to make it work?

mentioned in issue #890 (closed)

mentioned in commit dd71e3d1

mentioned in commit b3603e8a

mentioned in commit 03d263ca