Guest Column | August 4, 2015

Next-Level Communications Solves SCADA Problem For City Of St. George


By FreeWave Technologies

Water and wastewater treatment facilities around the globe are turning to the Industrial Internet of Things (IIoT) to help automate and improve the security of their facilities through high performance M2M wireless communications. In fact, there is a suite of Class 1 and Div 2 spread spectrum unlicensed and licensed radios specifically for water/wastewater applications, including high-speed wireless Ethernet, serial, and IO radios. These radios can be easily networked to ensure that facility monitoring and performance data are accurate and delivered in a timely fashion. These solutions can help municipalities design and implement a world-class point to point wireless network for unique facility applications including water and wastewater treatment plant monitoring, pump house control, chemical monitoring and control, SCADA systems, remote video surveillance and security, water flow control, and cathodic protection applications.

The problem: enabling the reliable and accurate gathering of data from hundreds of wireless I/O points scattered throughout a very large and diverse topographical area, while considering:

  • Wider area for source and use of water
  • Network type and arrangement
  • Protocols and conversions

Many municipal water systems have broadened the area from which they gather, use, and reclaim water.  Most growing areas have faced the dilemma of higher demands on services while trying to stay within shrinking budgets and manpower cutbacks. While many had earlier seen the need for wireless, high-speed data collection, it has only recently become a comprehensive necessity.

Several years ago choices were few to address the needs of wireless data gathering and logging.  Water utilities used a ‘one-size-fits-all’ unit with set parameters and made their systems adaptable to the technology of the day.  Now, a wide variety of equipment is available to render solutions of varying levels that are both backwards compatible, as well as on the cutting edge of wireless M2M communications and data collection. We’ll discuss issues faced while trying to minimize expenses, and methods to gather data wirelessly from a wide geographical area with diverse topography.

The first issue to resolve when transmitting data from one point to another is protocol.  In the context of wireless M2M data communication, a network protocol is a formal set of rules, conventions, and data structure that governs how computers and other devices exchange information over a network. In other words, protocol is a standard procedure and format that two wireless data communication devices must understand, accept, and use to be able to talk to each other.     

One protocol that has, for the most part, become a standard for a majority of devices is ModBus.  The ModBus protocol was developed by Modicon in 1978 as a simple way for transferring control data between controllers and sensors using an RS232 port.  The protocol describes an industrial communications and distributed control system developed to integrate PLCs, computers, terminals, with other monitoring, sensing, and control devices.  Since its creation it has effectively become the industry standard used by multiple control and wireless sensor companies. Today ModBus protocol is the single-most supported protocol amongst automation devices.  Most devices, being able to communicate serially, utilize ModBus or can be configured to do so.

ModBus is now also the most common IIoT Ethernet protocol Ethernet port 502 is now standard for the ModBus TCP/IP protocol.  ModBus is the only real open IIoT protocol owned by the industrial community. The ModBus protocol is a trademark of Schneider Electric.  However, Schneider Electric made the protocol specification and its implementation available for free to anyone who wishes to implement a ModBus or ModBus TCP/IP device.

When integrating older technology with new technology, ModBus protocol has been instrumental in enabling backwards compatibility.  Integration of data systems often will utilize this protocol for many areas where small pockets of data are to be gathered and transferred to the system’s ‘backbone’ before being sent to the main control and gathering area.  This is where the term SCADA was implemented: System Control And Data Acquisition.

The ‘backbone’ is typically a wireless M2M communications technology to allow for many data items to be transmitted bi-directionally at the same time.  The Water Improvement District in St. George utilized the FreeWave HT-Plus Ethernet spread spectrum radios for the backbone of its wireless M2M communications network.  This unit has proven to have a broad enough bandwidth to transmit high volumes of data at high speed, while also having the range necessary to minimize the number of repeaters needed to cover many miles of coverage area.

To minimize cost without sacrificing performance, the city designed a system using cost-effective FreeWave FGRIO and FGR series radios to handle single and low I/O data points using the ModBus protocol.  Then, these satellite cells are coupled together through a network of the HT-Plus Ethernet radios to the Main Control PC that graphically displays the data and logs the important points at predetermined intervals.  The HT-Plus radios have two serial ports which allow ‘back links’ for the serial data radios, enabling them to send data without converting it to an Ethernet protocol.  The city also use PLCs (Programmable Logic Controllers) at control points and configures those PLCs to communicate through serial ports to ModBus devices using the FGR radios, before connecting to the backbone through TCP/IP ports.

The system using these methods of coverage has a wireless M2M backbone system that is over 100 linear miles in length, and branches covering many more miles.  The I/O count is in the thousands, with more than two hundred data sites.  The sites are a mix of utility-powered and solar-powered devices, with the solar sites designed to perform for several cloudy days without interruption of service.  The combination of hardware with the ModBus protocol has also minimized the need to replace or upgrade existing field hardware.

The city also found that, more often than not, the larger metropolitan areas have more than one water district in the areas of coverage.  These areas may be county and city entities or several cities in close proximity.  To further minimize costs, local agencies have joined forces to form Memorandums of Understanding (MOUs) that will allow them to utilize the same backbone and/or data points, reducing duplication of effort.  This has worked well with the ability to secure separate systems, passing only data contained in the MOUs from one to another. 

As the world becomes increasingly connected, the integration of municipal water system devices and tools, such as sensors, process control devices, security cameras, and more have increased the need for well-established, secure machine-to-machine (M2M) communication and networking solutions. Many companies depend on effective communication technologies to reduce overhead costs and improve their bottom lines. Today, however, it’s not just important to retrieve and review the data gathered by these tools. Companies are now taking a closer look at their data and focusing more on how to leverage their command and control data networks to improve their operations and streamline workflows.