Editor's Choice

Control architecture leads to faster, easier product development for refrigeration

May 2024 Editor's Choice IT in Manufacturing

What’s the secret to providing superior service and staying competitive in a changing market? You might learn something from ALTA Refrigeration’s experience. Over ten years, it transformed itself from a custom engineering services company into a scalable industrial equipment manufacturer, using an edge-oriented control architecture to manage a growing installed base.

Where to start?

ALTA’s centralised control system design was built around an industrial PC running custom C++ code on top of a distributed I/O system from Opto 22. They then began exploring Opto 22’s newer groov EPIC system.

EPICs, or edge programmable industrial controllers, provide a new option for industrial control systems that combine the best features of PLCs and IPCs. PLCs offer a rugged, purpose-built design with many typically expandable, options for I/O and device communication. IPCs offer general-purpose processing power, storage and networking options to support more demanding applications and broader functionality like cybersecurity, database management, and high-level programming languages. EPICs support all of these functions on a single backplane, but without the complexity of maintaining a full Windows OS environment.

groov EPIC uses a custom Debian Linux distribution that has been stripped down to the essential components, reducing its memory footprint and potential cyberattack vectors. Additionally, it has been cryptographically signed with Opto 22’s private key to prevent installation of any unapproved software. However, Opto 22 also exposes access to the EPIC’s Linux command-line using the secure shell protocol (SSH) and a free Shell Access licence.

“All development is done remotely through the SSH connection in Visual Studio,” Peter Santoro, controls engineer at ALTA explains. The program controls the installed I/O modules − voltage and current sensing inputs and discrete AC outputs − using Opto 22’s C++ OptoMMP SDK or software development kit. The application also includes its own Modbus server that creates and manages connections to variable frequency drives, the local energy monitoring unit, and other remote devices.

“We also have our own REST API and webserver running on the C++ application,” Santoro adds, “allowing us to create our own web page interfaces in HTML and Javascript. Each EXPERT’s web interface is served up from its EPIC controller. It includes prebuilt templates for different unit configurations, and verifies system settings to help technicians identify configuration values that are out of range or not recommended. It also generates alarms as needed.

To create this site-level HMI, each EXPERT stores transient data in the shared memory ‘scratchpad’ area of its groov EPIC. ALTA’s HMI server runs on Windows, and uses Opto 22’s .NET OptoMMP SDK to retrieve this data from all units in one-second increments.

ALTA can also access this data remotely for troubleshooting recent events. By default, groov EPIC does not route traffic between its Ethernet ports, so ALTA can use the controller to create a security zone for each EXPERT. One port on each EPIC connects to a private network exclusively for the controller and its remote devices. The other port is connected to a common network between all the units at a given site and the local HMI server. This server is connected to the internet and uses MQTT to send and receive data, acting as a middleman for each individual EXPERT to the MQTT broker that resides in ALTA’s headquarters. When ALTA’s remote HMI requires new data, it sends a request to the local server over MQTT. The data is queried and sent back. External connections to local HMI servers are restricted, so that the only traffic allowed through is from outbound MQTT TLS connections.

Recently, ALTA also made it possible for its customers to access this remote server. The server has its own database that records temperatures and energy usage for each EXPERT in ten-minute intervals. Customers can log into a private web portal to generate reports directly from this data.

The coolest service around

ALTA has built a nationwide HMI that aggregates data from its network of EXPERT units, and highlights any issues the team needs to act on. Instead of spending hours every day checking on each site, they can monitor their entire installed base in minutes. They know when there is a problem, can input and track necessary work orders, track technicians’ locations, and monitor energy usage per unit. When an alarm occurs, the system creates an interactive timeline of events before and after the alarm.

“Often, we know what the problem is before the customer calls. We just need to drive there and fix it,” says Santoro. “With the amount of data we get from our units, we are capable of diagnosing the vast majority of problems remotely. This allows many of our end users to not staff on-site maintenance.”

To read the full version visit www.instrumentation.co.za/ex/opto1.pdf/ex/opto1


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