Real-time exchange of high-volume data between PLC controllers

New safety CPU modules that can now function as both a safety controller and a safety device are launched by ABB. The modules, when used with ABB's AC500/AC500-S programmable logic controller (PLC), feature the ability to exchange process and safety data, not only from one controller to multiple devices but also from one device to multiple controllers, using PROFINET/PROFIsafe shared device functionality.

Now hybrid interconnected PLC control systems can extend traditional centralised or distributed control. As such, each controlled machine can deliver high volumes of process and safety data in real-time, simultaneously, to several central control systems.

This approach replaces gateways which are expensive, take valuable control cabinet space and because they are limited to only 12 bytes of safety data per gateway, cannot communicate in real-time with large safety data volumes. With the new system, a maximum of 1440 bytes of process data including up to 384 bytes of functional safety data can be allocated for up to four PLC controller systems, thereby providing faster reaction to optimise production and improve predictive maintenance, leading to less downtime.

ABB's flexible and modular approach allows splitting a complex system into different tasks, such as central controls for production and for storage handling or automatic control and manual operator control desks. The data can be shared in real time from machines to different central PLC controllers.

Furthermore, ABB's system uses communication modules as add-ons for process and safety data exchange, thereby being able to flexibly modify existing systems via an extension for controller and/or device. With distributed control, where data flows from one system to another, the control logic is spread across the facility, which enhances the overall system performance. The new control approach allows optimisation of such systems to have all needed control and safety data available at a given time.

Flexible control systems

These new PLC modules target system integrators that are building complex installations, yet demand flexible control systems in all kinds of industrial applications. Typical applications include remote control of machines and equipment in harbors, airports, distribution centers and production facilities. Often in such industries, the control system is altered or updated to allow for production changes or extensions to the facilities. During such upgrades or maintenance, it is important that the central control systems are available. These could be manual locations with remote control access for unexpected occurences.

Now each machine can deliver the process and safety data in real time, simultaneously, not only to several central control stations but also to special control systems. For example, condition monitoring installations can now feature safety on-board that analyses the status of an automatic guided vehicle's brakes.

The modular architecture enables existing control systems to be extended with communication controller and device functionality. Furthermore, standard controller communication interfaces can be re-used by the safety controller. This reduces design complexity of the safety controller by separating the safety and standard control logic processing in the control system. With this approach, users can easily extend and modify existing controller/device topologies by using communication modules to realise safety and/or process data exchange between different control systems.

Yauheni Veryha, ABB's product manager for AC500-S safety PLCs says: "Safe remote control of machines is becoming common. Today, typical real-time machine control is done by communicating only to one or two controllers. In the future, the communication to at least four control systems will be required and later to eight or even more.

"With an increasing focus on collaboration, the next generation of automated industrial environments needs to be efficient, productive, scalable and safe. This solution goes a long way to increasing collaboration between machines, robots and people using flexible, safe and reliable communication."

For more PLC-related information, please visit www.abb.com/plc.