Data collection stopped

I had a data type problem in my MSSQL database table. I went into the MSSQL database table design and changed the datatype of a tag. At the same time i deleted a test tag (column) in the table. I did not delete the tag from the FactorySQL database.

After saving the MSSQL table, FactorySQL stopped collecting data and gave me an error message saying it could not find the tag in the MSSQL database that i had deleted. It looks like FactorySQL data collection for the entire group stopped.

To solve the problem i deleted the test tag from the FactorySQL database and restarted the group. Everything is running happily now.

Obviously i should have deleted the FactorySQL tag at the same time i deleted the MSSQL column. My mistake. But should the entire group have stopped scanning because of this error? If it did not stop scanning was the data cached someplace? I can’t seem to find it.

Thanks for the help.


Yes, groups, which are sometimes referred to in the documentation as “transaction groups”, represent a whole unit that is expected to be completed together. From a technical point of view, all of the items get put into a SQL INSERT/UPDATE query, and sent to the database. If there is a column in the query that doesn’t exist in the database, the database is going to throw an error, which in turn will be represented by a group error, which will cause the whole group to fail.

For this reason, FactorySQL checks the tables when the group is started, and asks to create any missing columns. If the columns aren’t created, the group won’t start- there would be no point, it would just error out.

Hope this was clear, please feel free to reply with any further questions.


very clear explanation. Thank you.