Static versus Dynamic tags

Dynamic tag addressing is when the PLC/device tag in the client uses the PLC address and does not match any predefined tag in TOP Server. These are "dynamic" because they are added during runtime when the client makes a connection. In many cases, projects are developed using dynamic tags because there is no OPC browsing method available, so tags have to be added manually in the client and putting tags in the server then the client is seen as double work. In other scenarios, individuals have developed effective ways of importing tags quickly from programming software right into the clients, so adding tags in the server is an additional step. In these cases, dynamic tags addressing is most effective for a project.

Static tag addressing is when tags are added into the TOP Server. These tag names (and not the PLC addresses) are then used in the client connecting to the TOP Server. A number of the drivers support pulling tags from PLC or its programming software (as is the case with the AB ControlLogix driver), so adding tags in the server can be a very effective way to build a project.  TOP Server also supports a number of ways to add tags quickly with the copy function or duplicating tags after one is created to help speed the tag creation process. It is always recommended that at least one tag under each device is created, so that communications can be quickly checked by connecting with the OPC Quick Client.

Implementing static tags can have a great advantage when a client is able to browse for OPC tags, as configuration in the client is simply a matter of pointing and clicking. It is also possible to export tag addressing as a CSV file both from the OPC Quick Client and TOP Server, and formatting these exports for importing into client software can prevent double entry of tags.

When converting a current project to TOP Server, most people go with dynamic tags as the projects are normally configured with PLC address. With new projects, there can be advantages to using Static tags. One is the ability to quickly test and verify communications with the Quick Client as noted above. Because TOP Server supports a number of different drivers, there can also be advantages to projects that are used with different PLC systems. In cases where an application remains the same/similar but the actual PLC type connecting to it is different at different locations, using static tags can have a great advantage. By naming the tags the same in two different TOP Server projects, the client program can be configured once for connection to the tags and different TOP Server projects can be loaded for different PLCs, and the client program doesn't have to be modified. You can even use the alias map (under Edit ⇒ Alias Map) to create custom names to the channel and device you create, so that different names can be used for the channel and device in your TOP Server configuration to help keep the projects separated, with the path/topic to the tags remaining the same for both projects.