hello,

I have multiple button on hmi screen. which are used for object selection, when I am going to press any button at HMI screen then I/O field at HMI screen shows object information and tags give the command to plc to fetch the information from SQL database and print it through printer.

problem is that, when I am select any object than this selected object not stable at HMI randomly alter by zero. change by zero only and reappear.

due to this, fetched information from SQL database is also become zero randomly.

and printer also print zero as per previous process.

i have multiple network where these selected object is reseted to eliminate the multiple selection of objects

so how can i fix it

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Split from Problem with changing PLC DB tag from HMI.

Which device fetches the SQL data?.. a PLC? the HMI? something else?

The data displayed on the HMI should be updated only at the moment when new data is fetched from the SQL. The displayed data should not be updated continuously as communication character may interfere here.

In the case where a PLC is in the loop, be sure that no overlapped memory is causing this issues. 

What are your thoughts? Which detail of your application do you think may be important to assist our volunteers to advise you?