SCADA System Components
In its most basic form a SCADA System may consist of (1) SCADA software (HMI) (2) some form of communications medium and (3) a device or instrument which communicates back to the SCADA software (Host). The method of communicating between the device the SCADA Software or Host is commonly referred to the network protocol. The industrial network protocol usually makes use of TCP/IP for modern systems. The industrial network protocol overlays the TCP/IP network which may be in place specifically for SCADA or shared by other infrastructure.
More complex systems may include PLCs and RTUs for plant control, IEDs for intelligent management and the switching of power equipment, drives, pumps, valves and other devices which may form part of a closed-loop control system. Sometimes the term Control System is used instead of SCADA System, however, more precisely a control system may exist and operate independent to any SCADA System. A Control System may not have any visualisation software (HMI). A SCADA System may also be used for monitoring purposes only and may not technically have a control system.
What does SCADA mean?
SCADA stands for:
Even though the system may be called SCADA, the CONTROL element may not be used. This is particularly true for passive instruments used to monitor the performance or operational status of a network of devices which do not have any capability to be controlled either remotely by SCADA or locally. This may be due the devices not having any inherent ability to control a process or because that particular functionality of the device is not implemented. For example, many systems monitor the status of locally automated pumps or valves, but do not allow for operator SCADA control of those devices.
Complex SCADA Systems
More complex SCADA systems may include redundant components like safety PLCs used for controlling critical plant, redundant communications paths between specific segments of the LAN/WAN or advanced applications that interface with SCADA (Enterprise Historians, Enterprise Asset Management systems, Workflow, Asset Performance Management systems, to name only a few). Complex SCADA systems can be extremely challenging to maintain if good standards are not applied at all layers of the system architecture. This includes how field devices are configured, how communication devices are managed and how all data elements in the system are defined.
Managing SCADA Systems Efficiently
Perhaps one of the greatest challenges of optimising an existing SCADA System for operation effectiveness, is being able to present information and decision criteria to the whole of business in such a way that the information is useful and intuitive. The purpose of presenting information to the whole of business is to widen the view of the information and empower more timely and improved decision making. The quality of the decisions based on SCADA System information is therefore linked to the quality of the system itself.
Unfortunately, for most existing SCADA systems, the standards applied to engineering have traditionally been oriented toward process control ie how the devices are managed from an electrical and instrumentation perspective. This is in contrast to naming devices based on GIS or Enterprise Asset Management system nomenclature. Names of devices, their location and other attributes should always be applied based on the established convention, however, when different parties add to a system, if the standards are not known or continuously applied, then inconsistency and therefore trust in the data quality becomes questionable. Although a lack of standards erodes trust in the system, the reliability of the information itself may not be affected. This said, either applying standards uniformly (fixing up the system) or masking the presentation of the information by an abstraction layer may be the more cost effective method to improve the user experience and confidence in the systems and information presented.
“Fixing up” a system for the sake of standards only for critical plant is likely to be accepted due to the risk of incorrectly operating an asset due to confusion with how information is presented. For critical systems this rarely occurs and these types of problems occur more frequently on non-critical plan or on plant that is built and operated by a third party on a budget and then at some future point transferred to the asset owner for continue operation of the asset.
Understanding what standards exist and how the standards have been applied is the most rudimentary step in any endeavour to update, improve and operate plant with minimal risk. Doing an independent system audit, which includes analysis of the system architecture and system design, provides clarity around the integrity of a SCADA System and any of the systems that rely on SCADA Software as a data source.
The system audit provides a basis for;
- developing strategies to implement new technologies
- identifying bottlenecks in the system in terms of data acquisition rates
- identifying unreliable components that may need additional redundancy components or to be replaced
- identifying methods to improve the data resolution and how information can be presented uniformally
- identifying cybersecurity risks that may place the greater business at risk
- presenting the current architectural issues and providing options for transitioning to an improved future state without necessarily starting from scratch
- developing recommendations based on stakeholder demand for better information for better asset performance or customer transparency about operations.
IOT Versus SCADA
Industrial Automation including SCADA Systems as the core component have revolutionised how organisations operate their assets. IOT or IIOT is set to augment, not replace how SCADA Systems manage these assets. Though IOT applications may cost effectively overlap in some areas where SCADA has been perceived to be too expensive to implement, the most important factor in Operational Excellence is the uniform presentation of asset information so that operators and users can trust their software application to do its job. The IOT application that controls your garage door cannot be compared to the complex SCADA systems that are used to put people in space, keep aircraft in the skies and prevent trains from collision.
Information Management and consistency of standards is key to SCADA Systems efficiency. You can ignore these standards at the start, but in years to come the cost to manage the SCADA System will become excessive. Too often Industrial Automation vendors have taken the blame for poor implementation of the SCADA Software. SCADA systems are replaced regularly simply because there is a perception that the core system doesn’t work. Putting aside that some products may in fact be more suitable for plant control and others more suitable for area wide (distributed) control, a degree of humility is required by asset owners to step back and analyse why their current investment in technology is poor before it is replaced. The stark reality is, that implementing a new system will require the same engineering effort again, and if standards are not applied, the same result will occur. The stark reality is that in addition to reimplementing the system there is a new cost to support the new software platform and any new interfaces the business may need to develop for the SCADA software.
Do I need to replace my SCADA System?
Based on the previous discussion, it’s a “yes” to replace the SCADA system when it doesn’t have the functionality or interfaces to the business systems you need to improve how your business works. It’s a “no” to replace your system (most of the time) if the reason for change is performance. Think very carefully before throwing out your existing system if the basis for change is solely related to performance as the issues are likely related to design, architecture, standards and discipline. A thorough system audit can provide confidence the answer is a “yes its gotta go”, or “no, just fix it!