Expression tag does not update

I put together a tag structure[attachment=1]BrickTags.xml[/attachment] that implements a finite difference model of heat transfer in refractory brick (one dimensional time dependent temperature in cylindrical coordinates). However, I find that one of the expression tags within the structure does not update when one of its base tags is updated. In the attached partial project[attachment=0]Copy_Of_Test1_2016-12-16_1828_partial.proj[/attachment], when the tag “Cp” representing the heat capacity of the refractory is changed, the expression tag “htMultiplier” does not update. The expression tag “M” does update. “Cp” is used to calculate “M” and “M” is used to calculate “htMultiplier”. Other tags such as “A”, “B” and “C” which depend on “M” do update. Any thoughts on how to resolve the issue would be most appreciated. Right now if I change Cp and want “htMultiplier” to update, I have to go into the tag editor and bring up the instance of “htMultiplier” and hit apply. Being new to ignition, I suspect there is something I need to do with respect to the scan class that I use for the expression tags.

I also link this post to an entry in the “requested features” as I am lazy and don’t want to upload the files twice.

I don’t know how to link the post to the new feature area, so I’ll describe it here. Another issue I have is that the tag structure suggests that I create a template to display the data of the “BrickNode” structure and another template “BrickWall” to display the data from the “Brick” tag structure. Naturally, I want each of these templates to be a drop target for their respective UDT’s. A “Brick”, as defined, has ten “BrickNodes”. Unfortunately, within the “BrickWall” template, I cannot assign the “BrickNode” UDT child tags of the template “Brick” property to their respective templates. It seems that “Designer” requires that “UDT” tags assigned to an object in a template be from an existing instance rather than from a template property. For the example, presented I explicitly assigned the “BrickNodes” from the “barrelBrick” instance. However, this will not work if I want to create multiple instances of the “BrickWall” template each displaying its own instance of the “Brick” UDT. The new feature I’d want is to be able to assign a child UDT tag of a template parameter to an object within a template. BTW, I’m using ignition 7.8 on a windows 10 machine. Other suggestions on how to achieve my desired aim would be most appreciated.

I finally found a solution to my issue :smiley: . The value of the expression tag htMultiplier is small (on the order of 1e-5) and was below the deadband set for the tag. I changed the deadband to 1e-6 and it updates just fine.

I also changed the layout of the templates that use the UDT structures “brickNode” and “brick” so that indirect tag referencing is used. I had not understood that UDT tags cannot be used in a dynamic manner.

For those with an interest, the tag structure could be used to track temperature profiles in steel billets or slabs being reheated in a furnace. Depending on the size of the furnace you might need several hundred “Brick” tags to represent each billet of steel in the furnace.

I’ve had a slight change in identity and find that I cannot mark this topic as solved. Would a moderator be able to do me the honors?