Unifying the process control network through a single gateway
04 June 2021
Greg Wainhouse, Field Segment Manager for Water at Bürkert explains how to optimise process control integration.
For wide-ranging liquid and gas control applications, commonality of hardware including valves and sensors guarantees performance through successful component integration. Connecting this hardware to the main PLC through a single fieldbus gateway reduces costs and can also be an opportunity to expand control capability.
The trend towards commonality of hardware within an automated control system increasingly includes process applications, from food & beverage markets through to pharmaceutical production. Previously, engineers may have specified a mix of ‘best of breed’ components or procurement teams might have selected individual items for best cost. The risk, however, is the challenge in integration, including the time it takes in commissioning and the accumulated cost. In some cases, attempts at integration may not succeed at all, with no single vendor able to resolve the issue.
Open digital communications compatibility
For engineers designing liquid or gas process applications, the advantage of a supplier that provides a full range of valves, sensors, mass flow controllers/meters and displays that can communicate via Ethernet, means assured integration between the components and the controller. Removing the potential for system errors and speeding up commissioning, a single supplier also reduces procurement costs.
Further to supplying a full range of valves, sensors and associated process control hardware, Bürkert’s ME43 fieldbus gateway is flexible for virtually all liquid and gas applications and the preferred communications protocol, featuring wide-ranging compatibility with Ethernet-enabled PLCs. This includes PLCs that communicate via PROFINET, EtherNet/IP, Modbus/TCP, PROFIBUS DPV1, EtherCAT and CC-Link.
Even if individual devices have Ethernet connectivity, linking each of them directly to the PLC incurs an additional licence cost for each node. The benefit of the ME43 is that licence costs are significantly reduced as hardware is channelled through the fieldbus gateway and then to the PLC, requiring just a single licence. Bürkert hardware communicates via the open source CANopen protocol, ensuring compatibility that also extends to third-party CANopen-based devices. Whether developing a new system or extending existing infrastructure, up to 128 inputs and outputs can be assigned to the ME43.
Analogue device integration
Third party devices, such as solenoid valves or sensors, that are not Ethernet-enabled can also be integrated to a Bürkert system via the ME43, thanks to a range of I/O cards. These enable the fieldbus gateway to receive analogue input signals, such as a standard 4-20 mA signal or 0-10 V through to pulse outputs common to previous generation flow meters, and then convert them to digital signals. While Bürkert provides a wide variety of process control hardware, this communications flexibility means operators are not locked in if they want to integrate a specific third-party manufacturer’s device.
This capability enables straightforward extension of existing systems, while new projects can be developed using various currently available devices, such as paddlewheels, that often only provide pulse outputs. This also satisfies the requirements of engineers who prefer analogue or pulse devices for fault diagnosis, using a meter rather than a laptop connected to the PLC.
Improved installation and commissioning
The ME43’s digital output relies on just a single cable, significantly reducing the cost of wiring and the time required for installation, which also makes maintenance easier. Similarly, the speed of commissioning is far faster and Bürkert’s Communicator is a single piece of free software that can configure and manage all PLC-connected devices via a laptop, which also allows remote connectivity.
An advantage for commissioning and maintenance via CANopen includes Bürkert’s expansion of the protocol to include additional status indicators. Using industry standard signal outputs, potential errors, such as valve opening and closing times, can be presented using recognised alerts displayed via Communicator as well the majority of devices.
The ME43 also includes control capability of its own and can manage segregated parts of a plant operation, like dosing on a skid as well as graphical programming for the automation of sub-systems. Graphical programmes can be created within the gateway to manage operations such as water level monitoring involving a pump and PID loops controlling upper and lower setpoints. In this way, the ME43 can also be used for distributed control to peripheral areas of a plant and if required, two or more ME43 units can be combined in a daisy chain and fed through to the central PLC. This also frees up processing capacity on the central PLC and segregating control adds a layer of security for selected operations should the central processor fail.
Commonality of hardware under a single device that can manage communications ensures integration for lower project costs as well as faster commissioning. With extra monitoring and control potential, the ME43 combined with Bürkert’s full range of valves, sensors and process control hardware is more than just a field bus gateway: it provides system performance and long-term reliability.
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