Tags Locking Up

I noticed certain string tags would, in Designer, report values of NULL and hence case a record to have a quality code of 0. There appears to be nothing wrong with the transaction setup or tag (both have been working for some time). When I went to the Quick Client and did a read for that tag, it started showing up in designer and hence the database correctly. Any ideas what’s causing this and what to do about it? It appears only to be happening with string tags read from SLC5/05 processors at the moment. We’re currently running version 7.3.3 (b570). Thanks

It is possible that there is an invalid SLC ST address in the transaction groups.

The AB drivers optimize the reads. In other words it groups like addresses into one request instead of separate requests. For example ST20:0, ST20:1, … are all grouped into one request. This is done to minimize the number of requests which improves speed and reduced workload on the processor.

What happens is if one address in the the request is invalid such as ST20:3 is not valid, then the whole request will fail.

I will need more information to narrow in on the source. Can you reproduce, turn on the SLC device logs and send them in?