How to get information about particular variable type and read_only flag?

[mglowinski93]

I'm using Read method to get variable value.
Such a response, however, seems to have no information about the type of variable or information about whether I can write something to it or not (if variable is flagged as read only).

Is there a way to get such an information related to particular variable?

[dmroeder]

Try GetTagList(), find your TagName in the returned results. Look at AccessRights

https://github.com/dmroeder/pylogix/blob/master/pylogix/lgx_tag.py#L32

[mglowinski93]

Thank you @dmroeder for a tip!

Nevertheless, I've one more question.
For Micro820 I always get None as AccessRight, even for _IO_EM_DO_XX inputs.
Do you maybe know, which value should i expect here when a variable is marked as read only in PLC?

[dmroeder]

For some unknown reason, those status tags seem inaccessible externally in the Micro800 platform. Same with local variables. There are a number of things that they did right with that platform, better than the high end controllers, but they limited other things for some reason.

AccessRights none mean no external access, so it won't return a value. There is an AccessRights read only and read/write. If the tag is read only, you should be able to read it, just not write. The status bits on micro800 might be different though

[mglowinski93]

Thank for explanation.

There is an AccessRights read only and read/write.

So, for ControlLogix family, I will get read only string as AccessRight attribute value when PLC variable is read only?
Sorry for primitive question, but I don't have ControlLogix to check it on my own.

[mglowinski93]

bump @dmroeder :)

[dmroeder]

Hmm, it appears that AccessRight is only being looked at for UDT definitions, not instances of tags. I need to do some further digging...

[mglowinski93]

Ok, so the summary is that I can't get the right access of a tag like i do with tag type at this moment ? Even for ControlLogix family?

[dmroeder]

You are correct. Sorry I misspoke earlier about this.

[mglowinski93]

Ok, thanks for clarification.
Will you create an issue related to this topic or this is minor issue and no time to handle that?

[dmroeder]

Currently, I'd say the latter. I have a few things in the works will keep me busy enough.

[mglowinski93]

ok :)