About the author
Charles Williams – Strategic Business Director, Grontmij
MIET CEng BSc Electrical and Electronic Engineering
Charles has over 25 years experience in telemetry, SCADA, instrumentation, control and automation in the water, transportation and nuclear industries. He has supported the WITS initiative since its inception and is currently the Chairman of the WITS DNP 3 Protocol Standards Association committee.
The need for a standard protocol
All UK water companies use telemetry and SCADA to monitor and control their remote assets. Traditionally, telemetry consists of a “Field Device” which is linked to a “Master Station” using a variety of telemetry protocols and communication methods. This provides data and information for the purpose of monitoring and controlling the process and the associated plant.
During AMP 6 water companies are placing more reliance on telemetry to provide the required data both to improve their operational efficiency and customer service. So there is an increasing need to have common standards for telemetry such that the required data can be collected in the most efficient manner.
The development of the WITS-DNP3 protocol standard
Hence the WITS DNP 3 Protocol Standard was developed for communications between Field Devices and Master Stations. The standard protocol would be of enormous benefit to both water companies and suppliers. Water companies would benefit from increased product choice, reduced cost, simpler configuration and improved data quality. Suppliers would benefit from greater market opportunities and the potential to reduce development and support costs.
Development and Availability of WITS Products
WITS compliant Field Devices are available from Xylem, Schneider Electric, HWM Water, Metasphere, Servelec Systems, Technolog, ABB and Brodersen.
The range of devices does not only include telemetry outstations and loggers, but also specialised devices such as pumping station managers, CSO monitors, and flow meters. This is realising the original vision in so much that the protocol would be adopted across a range of Field Devices to enable them to connect directly to the associated Master Station without the need for a separate outstation.
Product Certification Process
Vendors may choose one of two levels of certification for their products:
- Self-Certified – whereby tests are conducted by the vendor using their own test equipment. Tests do not involve any third party.
- Verified – whereby tests are carried out against existing WITS Verified devices in conjunction with the vendors of those WITS Verified devices. This ensures a greater level of confidence that the equipment complies with the protocol and delivers interoperability.
Future Developments and International Adoption
In order to ensure the Protocol continues to meet the requirements of the water industry, the WITS Protocol Standards Association was established which is dedicated to the collaborative development, maintenance and promotion of the WITS protocol. This is guided through a long term Strategy that encourages vendors to bring WITS based devices to market, maintains ongoing development of the protocol aligned to users needs including the requirements associated with data security aligned to CPNI best practice.
Further afield the Water Services Association of Australia (WSAA) is developing a set of guidelines for the deployment of SCADA on water utility assets within Australia. The purpose of the project is to establish some form of consistency within Australia and to give those wishing to better manage their water assets by implementing SCADA on their water services some guidelines as to what is minimum, good, and best practices. It will cover the whole lifecycle of SCADA from planning, design, procurement, deployment and maintenance through to disposal.
It is recognised that the communications protocol used in a SCADA system is a fundamental requirement for interoperability, flexibility and efficient data gathering and control of the assets. The communications protocol recommended by the WSAA guidelines is DNP3. Although originally designed for the power utility sector this protocol has become the de facto standard for many water utilities and is used widely throughout the UK, USA and Australia. The WITS standard, building on the DNP3 standard, provides water utilities with many water utility specific enhancements that are not addressed by protocols from other utility sectors. The WSAA has recognised the benefits that may be gained from the WITS enhancements and the guidelines will recommend the use of the WITS standard as “best Practice”.