SCADA systems have undergone numerous evolutions since their inception many decades ago. Innovations in technology and control systems have led software developers to develop new SCADA software to keep up with the changing industrial workplace. Data Modeling is one of the many new features some of the pioneering SCADA developers are introducing. The idea is that the complexity of large systems with numerous assets can be reduced, making the entire systems more understandable and manageable using a data model.
Anyone involved in process automation has had the misfortune of trying to make sense out of many different types of data from many different sources. When HMI screens are bound directly to data coming from PLCs, there are several problems that can emerge:
- First of all, creating the screens and data bindings requires an intimate knowledge of the many memory addresses in each logic controller – this means there is usually only one individual or a small group capable of creating or modifying the screens.
- This also means that the PLCs have to be running and returning live data while the HMI screens are being set up – this can lead to unnecessary downtime and more complicated deployments.
- Any change in the process or processes requires a time significant investment in modifying the HMI displays to coordinate with the new data.
With a little imagination, I’m sure most people can think of several other drawbacks to binding HMI graphics directly to PLC memory addresses.
How Does Data Modeling Help?
In the world of SCADA, a data model is a logical representation of a real world system. A data model contains instances of all assets that are to be measured, along with properties of those assets (i.e. temperature, velocity, volume, etc.). When using a data model, HMI graphics are bound to properties of these assets rather than the actual data. The actual data is read to the model and the HMI updates accordingly.
Data modeling provides a number of advantages:
- Creating HMI screens and data bindings does not require knowledge of the specific memory addresses since the graphics are bound to the model – screens can be created quickly and easily
- HMI screens can be created independently of the PLCs – this means the entire SCADA system can be set up without having to take the process down.
- If assets are lost or changed – or new ones are added – simply update the data model and every instance of the asset can be modified simultaneously – this means HMI screens can be reused instead of recreated, saving countless hours of development and training time.
- A well-designed data model can give a unique overall perspective on a process that makes it easier to make plans and decisions about how the data can be used to make improvements.
Data modeling also allows new types of data to be monitored and controlled. Your data model can include work orders, purchase requests, human resources, supply chain data – in short your entire enterprise can now fall under the watchful eye of your SCADA system. This creates whole new possibilities for management and strategic planning.
Case in Point
Consider a recently developed SCADA application from B-Scada: Status Enterprise Edition. Status Enterprise allows users to create a logical model of their enterprise, including everything from equipment to users. Each type of equipment can be created with all associated properties, alarms and historical records. If there are 1000 instances of a particular asset, just create the type once and automatically generate 1000 instances of it. Assets can be grouped into collections, or one asset can be subordinated as a component of another (i.e a motor that has a cooling fan as a component). Work orders, maintenance records and troubleshooting guides can be created and associated with particular assets.
Aside from making data more manageable, modeling can also make creating HMI screens much easier. Imagine you have 1000 motors that each have a unique temperature value, a unique RPM value, a unique asset tag, etc. Since each of these motors is an instance of the same type, one screen template can be created for that type. That template can then be used to create 1000 unique screens for each instance of that type. This can save a tremendous amount of time (and money) in developing or updating a SCADA system.
Data modeling is not a new idea, but it is fairly new to the world of SCADA software, and it seems a safe bet to assume that it is not going anywhere. In fact, it’s likely that it will eventually be the way that all SCADA software operates.