DPEs update problem with S7plus

[andrea.bertorelli]

Hi, I've several variables that are activated / deactivated when opening panels, there are a few dpes (about 6-10) that are activated and subsequently deactivated.

Often happens that the "active" variable does not read the last value on the plc, despite being polled at 2 seconds (there are about 200 active dpe in the whole program so the plc load is not heavy).
It works neither with the low level comparison nor without it.

After several weeks I still haven't found out why, the workaround to get them working again is to "put them in subscription", leave them for about ten seconds, and then put them back in polling. But after a while of opening and closing the panel, they stop working again.

I noticed today, however, that from the configuration of the s7plus connection, every time I do a GENERAL QUERY (GC), these update me the value that is present in the plc, but for example, if the value changes every 10 seconds, the variable is updated only once when I do the general query. To get it back to work I have to use my workaround.

im using a 1515 plc, with 2000 subcriptions limit.

Do you have any idea why this behavior?

[gschijndel]

Is it not an option to use 'Polling on Use' instead of (de)activating the variables?

Look in the documentation under: Drivers -> Driver specific functions -> Poll on use

[andrea.bertorelli]

Hi!
Unfortunately not, because they are dpes that we rarely use, once a month, so for a license issues its basically useless to keep them active and not used.
When we have to change some settings of the plant, once at month, sometimes they dont work.
They are "activate", but do not load the last value from the plc, they only show what they had when they was deactivated.
The only way to "unlock" them is to go to the para, deactivate them by hand, change the type of direction(polling -> subscription or whatever), and restore the one in polling.

Subscriptions still give us the same problem.