Traditionally, PC-based scada systems were the only tool in the instrumentation and control engineer’s toolbox for plant process visualisation and control applications. This led to many facilities implementing scada systems simply because there were no available alternatives. To make matters worse, many continue using these unnecessarily costly and complex systems, even as alternatives emerge, out of force of habit.
Ian Loudon, international sales and marketing manager at Omniflex Remote Monitoring Specialists, discusses why plant engineers should replace outdated scada systems with new operator interface terminal (OIT) and human machine interface (HMI) systems.
Historically, PC-based scada systems were the go-to choice for visualising plant processes and providing control room oversight of ongoing plant operations in small and medium-sized plants. While these are functional systems capable of performing the required operations, they are unnecessarily costly, with plant managers required to pay per I/O point and pay annual subscriptions, ongoing Windows operating system licence fees, ongoing maintenance contracts and any specialist support fees. To make matters worse, they also involved surrendering control and maintenance of the scada PCs to IT departments which often do not appreciate plant operational requirements.
Despite the drawbacks of scada, many engineers were hesitant to move away from the systems as alternatives became available because, if nothing else, scada systems got the job done reliably. However, as alternative technologies such as OIT and HMI systems evolve, the case for replacing scada systems becomes even more compelling.
Offering choice for engineers
While process control systems provided OITs for HMIs dedicated to specific hardware, they were standalone and tied to a specific PLC manufacturer. An unfortunate fact is that many applications have deployed PC-based scada systems simply because there was no other choice.
However, the advent of vendor-neutral OIT/HMI displays in a range of sizes with touchscreen displays and plant-hardened HMI technology, suitable for both the control room and factory floor, has added another tool to plant engineers’ toolboxes. These systems allow for distributed control to local points while bringing only key parameters back to the control room, reducing control room operator workloads. This is ideal for applications such as water pump monitoring, where control room personnel simply need to know live water levels and whether the pumps are on or off.
Another key advantage of OIT/HMI systems is that they are more robust than traditional scada systems. With an OIT/HMI system, there are no hard drives that can fail, no Windows operating system to support, no networking issues and no inherent cybersecurity concerns, something that continues to be a growing worry for many businesses, particularly around mission-critical infrastructure. This makes OIT/HMI systems well suited to applications on a nuclear site, where local engineers need to immediately know ongoing system status so they can act accordingly, and there is no advantage to having a networked PC-based scada system in place.
Omniflex’s EasyView range of HMIs can communicate with a variety of PLC and PAC hardware, and provides engineers with a flexible system to manage plant operations. EasyView HMIs come equipped with free configuration software, require no ongoing costs and, crucially, are simple to use. Realistically, plant managers using an EasyView HMI solution can save around 80% of implementation costs compared to using a traditional scada system.
The touchscreen HMIs range from 5 inches to 15 inches depending on the application and space constraints, and are compatible with over 300 PLCs. Alternatively, HDMI-capable displays such as large flat-screen TVs can be used because the EasyView technology offers HDMI Full HD 1080p capability. This allows plant KPIs to be displayed front and centre at all times, keeping personnel focused and up to date with ongoing operations.
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