Retain problem
Hi,
Some times i add a new retain variable, event under Fast edit mode (and download changes only) the "old" retain values/variables are cleared/re initialized.
Is something we have to ignore, or is it a bug in the PLCnext engineer?
it's not all time, but sometimes it comes 3-4 times in a row....
- Emil
Comments
Hi Emil,
Are you able to provide information that would allow us to reproduce this problem?
e.g.
Thanks.
~ Martin.
Hi Martin
I have seen it in PLCnext 2020.0.1LTS, HW: 02 FW: 2020.0.1 LTS
Update
In the new 2020.3:
Fastedit mode:
If i add a new variable, select/unselect retain, and download the whole project, and the plc restarts, every time all the retain clears/reinitialize....
i have tried 4 times in a row, and the same result.
in download changes it seems to work.
I have made a video about the problem:
HI Emil,
Here is the response to the problem demonstrated in your video:
=====================================================
When you "Leave Fast Edit mode", the controller stops and transfers the changes. If changes are made to retain data, a CRC error occurs in the retain data (see screen shot below), and the controller starts with a cold start, which results in a reinitialization of all retain data to initial values.
In order not to lose any retain data when changes are made to retain data, the only option is to complete the changes with "Leave Fast edit Mode (changes)". The change is then transferred during runtime and there are no CRC errors.
=====================================================
I hope this helps.
~ Martin.
Hi Martin.
Thanks for looking in to this problem. BUT.....
If i make a change later there will be in a size/hw change or similar, i will loose all retain data, and that is a big problem.
I have experience that the download changes not always working.-
In that case i will lose all data......
Is it possible to "record" all the data, a easy way, and put it back in to the controller afterwards?
Hi Emil,
The PLCnext Runtime does its best to restore retained data to a project when it can be sure that the retained data is valid, i.e. that the data can be safely restored to the next version of the project that is loaded to the PLC. It must err on the side of caution - it is better to lose retained data, than to mistakenly load retained data to the wrong variable(s).
But perhaps the decision on when to restore or discard retained data can be improved. If you can demonstrate a situation where retained data is lost, when you think it should not have been, then I can ask the developers to look at that situation.
If you would like to implement your own data backup/restore mechanism, then I am not aware of a simple way to do this, but perhaps other Community members have done this themselves.
~ Martin.
Hi,
Emil, unfortunately you are not the only one who has problems with retain variables...
Save to file is the only safe action to do in this situation.
Hi
For me it's still a mystery why it normally works in download changes, and not ind full download.
It make me remember a PcWorx version there had a similar problem, there make a fault with Retain, and coldstarted the PLC....... That was more than 1 year before a new version was released there fixed that problem.....
As far as i can see with the progress of fixing problems in PLCnext, we are looking at the same time frame.... And that's not god enough.........
Compared to PcWorx 6 that i'm used to, there is so many problems compared to the old software.
Tags copy/paste/import/export to excel fx.
Zoom functions, (remember zoom, fixed zoom at start up fx.)
Global variable auto
Retain works like crap. When the system is up and running with datalogging of power and so on, the data can and will lost sooner or later, when i make changes.
I was impressed at the start of PLC next, but 2½years after it still missing functions, and the most basic things are not working, or not so we can trust it.
At the moment i have 6 controllers in develop, but when they are in production, i'm scared to make changes to them, with risking data loss..... Just all the timer values and user setpoints there are changed after i',m finished the programming.
i will say at the moment i'm done with PLCnext.... There is so may issues about simple stuff there is not working.
-Emil
Hi Emil,
thanks a lot for your feedback and please be sure, that I can understand you.
To clarify the retain behaviour:
It doesnt matter if you make changes via fast edit mode or dwonload all or downlaod changes.
When the retain memory layout is changed, the retain memory is initialized at this moment.
The problem you refer is not really a problem or a bug, it is a not implemented functionality. This functionality was calleed "extended retain memory handling" in PC WORX 6 with the PC WORX PLC's.
Actually the collegues from the firmware department are developing exactly this extended retain handling for the PLCnext targets. The sceduled release date for that is firmware version 2020.6 .
Please excuse the the actual progess in devekloping features to the PLCnext technology does not meet your expectations.
We are all working hard to become better and to put the efforts to the functionality which is needed by the market.
BTW: We are also working on the interface to export/import global variables to *.csv files till PLCnext Enngineer version2020.6
The auto generation of gobal variables is doen, also the auto generation of external variables based on a choosen global variable.
Zooming - I know that you reported me a zooming problem with Windows 7 - but this does not happen with Windows 10 and unfortunately Windows 7 is out of scope.
In any case of further feedback or requirements in regards of PLCnext Engineer, please dont hesitate to contact me directly.
Best regards
Carsten.