Thanks for the input Marie. The problem is, I want the trend/faceplate to be truly generic, so I can click on any data field on a display and up will pop a faceplate with all loop/ motor start-stop/ valve open-close controls.
If I can put all of this information into a parameter file then I can re-use this 'faceplate' for all of my similar type tags.
If I type the tag ie. LIC001 into the label field it will always read that, so if I click on TIC001, it will still read LIC001. The only way I have found to do this is to create a simple memory tag of string data type. Memory tags do not add to your tag count, and I can just set the 'initial value' to LIC001. Since this is a loop faceplate I am working on, in my parameter file, I have #1-#6 with each of those being a loop property (SP,PV,CV,AUTO/MAN, ALARM, and TAG)
My problem now is some loops don't have alarms, and some we don't want to provide access to the A/M controls. If I leave them out I get a warning in the activity log and it screws up the graphics if the tag is not found. I thought there was a way to just use a value in the parameter file and I could use that to make things visible/ invisible, but I haven't found a way to do make that work yet.
As for your question, I didn't use a placeholder, I chose a DataLog for the 'model' that these tags reside in. We have 2 datalogs for each area of the plant, one for discrete-on/off values, and one for analog values, so the way I am doing this, I will need a different generic trend for each plant area.
I'm gaining though. My predecessor was making individual faceplates for each loop(hundreds, if not thousands)! Also, he made a trend with all tags from the datalog, so you would need to go in and disable all the tags you didn't want to view. A real pain and alot of different graphics to keep track of. This is still a pain, since you still have to make all of the parameter files, but it's not too bad. Maybe I'll find an easier way someday!