An important aspect of developing a flexible SCADA or HMI application is determining the number of tags the project will require. In InduSoft Web Studio, license levels are broken down by tag count, which makes it an important variable in choosing the license required for the project. Deciding how many tags are required will be an important step in creating an HMI or SCADA application that includes all the necessary functionality and also leaves room for further development.
Because every project is different, the number of tags will vary widely from application to application, but in general, there are some major aspects to consider when coming up with a rough estimate of the required tag count.
- How much data do you intend to manipulate? Is this a small HMI designed to run on a 5.7” panel PC, or a SCADA scale operation that includes communications with PLCs, trending, and historical data? By understanding the scale (and potential scale) of the project at hand, it’s possible to begin refining the possible tag count required.
- What equipment are you using? Each PLC or controller may include multiple I/O options. These do not always correlate to tag numbers. For example, if a PLC has 50 I/O slots with 16 I/O points each, totaling 800, it’s a good rule of thumb to plan to use two to three times as many tags in the application.
- Leave room for expansion. If you intend to develop your application further in the near future, or scale it for new devices, it may be a good idea to leave room in the tag count for additional changes to the project.
Choosing your license level
InduSoft makes many different license levels available, making it easier than ever to choose a reasonable tag count for your project. There are options for anywhere between 150 tags to 512,000, with many breaks in between. Whether you are working on a small project or a large one, it’s possible to choose a level that will include all your required tags, without forcing you to purchase substantially more than you will use in the application. Don’t hesitate to contact InduSoft at firstname.lastname@example.org for more information if you need assistance in determining how many tags you will need for your project.