Remote Monitoring with Legacy Equipment

The foremost application of the Industrial Internet of Things is remote monitoring. With the help of MQTT, the grain industry demonstrates how to leverage a multi-protocol, legacy architecture for IIoT.

One industry you’re least likely to expect to be at the forefront of the Internet of Things (IoT) would be the grain industry, but that just so happens to be the case. And it’s not so surprising when you realize the U.S. market for food grains is approaching $10 billion. Operating in a market of that size requires modern automation systems.

In 2015, Automation World reported how Riceland Foods deployed an IoT system to monitor hundreds of sensors to boost operations and safety, reduce downtime and deliver operating intelligence for continuous improvements. Now, Smart Grain Solutions, a provider of grain moisture control products to the grain industry, is using message queue telemetry transport (MQTT) to improve how farmers maintain the proper level of grain moisture, dry the grain when it is too wet and alert them if spoilage or hot spots develop in grain storage bins.

Knowing that current grain monitoring systems on the market can only read specific brands of temperature and moisture cables, and that each bin monitored requires a dedicated controller, Smart Grain Solutions saw an opportunity. The company set out to develop a controller that could read a wide variety of cables and sensors and use a PLC system to remotely monitor and control an entire grain storage site versus just one bin. The system envisioned by Smart Grain Solutions would allow a farmer to use any sensors and cables they already had, rather than being forced to replace their legacy sensors and cables to use the company’s new controller.

Just as in the manufacturing and processing industries, the agricultural production industries connect their SCADA/HMI systems either directly to controllers or through an OPC server polling the PLCs in their native protocol over a network connection. As a result, the agricultural industries encounter the same issues related to interoperability, bandwidth and security as the manufacturing and processing industries. To create the multiprotocol system Smart Grain Solution envisioned, the company turned to system integrator APQ Engineering for help.

APQ Engineering's Nick Skoog and Aaron Lehto used MQTT to avoid the common method of polling for PLC data over the network. Instead, using MQTT, they implemented an edge-initiated message oriented middleware (MOM) architecture. This approach decouples the data from its originating source by storing it on a middleware device that can be polled as needed. This type of architecture avoids the interoperability requirements common in remote monitoring and control architectures and eliminates the bandwidth interference that can affect the performance of field devices when polled directly for their data.

Read more about how MQTT enables a MOM architecture to sidestep interoperability and bandwidth issues.

The complete system that Smart Grain Solutions wanted would require secure, flexible HMI/SCADA software capable of acquiring large amounts of I/O over cellular technologies. To accomodate their vision, APQ Engineering chose Inductive Automation’s Ignition HMI/SCADA software and Cirrus Link’s MQTT Modules for Ignition.

In developing the system, APQ installed the Cirrus Link MQTT Transmission Module and Ignition OPC Driver in a Beckhoff PLC, which can be located at the grain elevator or storage facility. The PLC connects to a Cirrus Link Chariot MQTT Server over a cellular or wired network where the Ignition platform subscribes to the PLC data as a client using the PLC’s installed Cirrus Link MQTT Engine module.

APQ's Skoog and Lehto explained why it opted to use MQTT over traditional methods:

  • MQTT is much faster and lower cost to set up than polled connection methods.
  • The MQTT engine and transmission modules integrate very well with industrial controls, eliminating the need to program or maintain highly specialized IT systems.
  • Published tags from MQTT allow rapid commissioning of remote sites. The tags are automatically added to the SCADA system and then quickly linked to templates on the graphic displays.
  • The low bandwidth of MQTT publishing data was critical to cost effectiveness for sites that might rely on cellular connections when compared to polling.
  • Remote sites do not need static IP addresses, thus making it easier to implement and more secure with client-initiated communications.

Smart Grain Solutions says that its system combining Cirrus Link MQTT and Ignition has significantly improved and automated storage facilities for its farming customers by helping them reduce shrink, deliver grain at optimal market value, maintain awareness of what’s going on in a bin, view trending data, receive status alerts and notices, and reduce energy costs.

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