RSView32: how can I datalog and view a string tag?

[RFurey 0]

I would like to datalog and set up a historical trend to view the data in RSView32. As well as the usual analog tag values I would also like to be able to log and view a string tag. I can datalog the string no problem, but I can’t figure out how to display the logged string value in such a way that it will change as I scroll back through the historical trend. It doesn’t have to be part of the trend, it can be a separate field. Another possible solution would be to use datalogrenamefile. Instead of recording the string in the datalog file (every ten seconds), I could create a new log file every time the string changes (twice a day) and use datalogrenamefile to add the string to the end of the datalog file name. If I could display the file name that is currently being read by the trend, that would work also. I have to warn you though - I’m a RSView hack, self taught. I don’t know VBA and I’ve never used any ActiveX. I’m hoping for a simple solution that has managed to elude me using the regular ol’ tools available in RSView. If not, I’ll go to plan B... if someone can suggest what that might be.

[RFurey 0]

I'm giving this topic a kick in the hope that someone may respond. If not, I'll let it die a quiet death.

[Guest]

Greetings Rodger, first question: how many strings do you need to keep in the log? ... let’s assume (gosh I hate that word) that the answer is 10 ... next question: when string number 11 eventually gets logged, is it OK to automatically delete the oldest string (number 1)? ... let’s assume that the answer is yes ... does the PLC that you’re using have enough memory available to store all of the strings that you require? ... let’s assume that the answer is yes ... if all of my assumptions are correct (or at least pretty close) then maybe you could approach your problem this way ... program the PLC to maintain the log inside its memory ... then use an RSView tagname to “point” to the particular string that you want to display ... you can do this by using the value in the tagname as part of an “indirect address” to tell the PLC which string you’re interested in at the moment ... as the RSView operator changes the value in the pointer, then the strings could be made to scroll on the RSView display ... you could also use a similar approach by storing the strings within the RSView computer (rather than inside the PLC) ... basic idea: it’s been awhile since I’ve worked with it but if I remember correctly, the RSView “Historical Trend” feature handles “numbers” but not “strings” ... (but maybe that’s been improved lately) ... if not, then you’ll probably have to think outside the “Historical Trend” box to handle your strings ... hope this helps ... best regards, Ron