I thought I understood class-based vs classless objects, but I do not understand this behavior. We have a class-based unit module for a vessel which has the typical assortment of phases, operations and unit procedures and I can "look under the hood" with Control Studio to examine configured parameters (or mis-configured). There is also a companion phase to manage arbitration, containing a couple of equipment modules for some header and valve control, shared resources. This arbitration unit module is apparently "classless" since my attempt to open with Control Studio indicates that I was "trying to open a Classless Unit Module [which] cannot be opened from Control Studio". The EMs that were inside were little better, they did open, but revealed only the COMMAND 00000/00001 sequence actions, but not the function blocks and interconnecting wires. But I can open other types (e.g. control) of modules that are standalone (classless), but not this unit module. Well, the only way I could figure out to satisfy my curiosity was by examining an FHX file I had exported which then revealed the wires and function blocks I couldn't convince Control Studio to reveal. The only other "trick" I could think of (which I haven't tried) is making a throwaway copy of the UM in question, deriving a throwaway class from that and opening that in Control studio.So I do wonder why Control Studio is prevented from opening a classless unit module, even if it needed to do so while maintaining "read only" restriction, similar to an object not being checked out, like if there was a reason to prevent editing. This seems odd, as the object would not seem to need to be frozen, much less rendered non-visible. This is on V13 & V14, if that matters. BOL didn't seem to have much to say about that. And this is a big system, so this could be locally imposed, from our corporate engineering for instance (we are a bit removed in both time and distance from such things).Thanks in advance for anyone's guidance, this appears to be an aspect of DeltaV configuration I had not previously encountered nor become knowledgeable about.
For Command driven equipment modules you can still view the function blocks but that is not the default view. Go to the View tab and select "Show as FBD" to view any function blocks at the top level of the equipment module. You can switch back by selecting the Show as SFC button next to it.
To view any embedded blocks you will need to select from the tree typically on the upper left. If you don't see a tree view make sure Hierarchy View is checked and also click on the Arrange button to reset width to their default in case things were shrunk.
As for opening classes Unit Modules in Control studio on-line. For a number of versions classless Unit Modules couldn't be assigned to controllers. I forget which version added that function. However, while you can assign classes UMs to controllers and download them there currently isn't really anything usable that can be access while on-line. You will just have the basic parameters involved with housekeeping of any module running in the controller.
These can be access by other modules or viewed using WATCHIT or OPCWATCHIT but you can't add parameters to a classless Unit Module so there can't be any customized logic in it. Since this is an "arbitration unit" I would guess it's being acquired through the Batch Executive as classless Unit Modules do still have an Equipment ID. To make any changes to the owner you would have to execute 4xxx series request codes from phase logic to acquire and release the unit. You can view ownership through the Batch Arbitration graphic in Operate or Live.