Cloud-Based Control System Delivering Cost-Effective Solutions

Project Summary:

Environmental Operating Solutions Inc. (EOSi) designed a reliable, cost-effective control system capable of being deployed quickly for both pilot and long-term projects with a minimal site footprint and impact to operations. Additionally, EOSi aimed to create a user-friendly interface accessible by remote and local personnel.

Problem:

EOSi needed to design a cloud-based SCADA using IIoT edge devices and MQTT capable of making cloud-based control possible, extremely cost-effective, and reliable.

Solution:

The infrastructure that supports the cloud-based control system starts with a Windows server installed on an Azure Virtual Machine (VM), which in turn hosts Inductive Automation's Ignition platform. The Ignition platform includes a full-blown historian utilizing an Azure SQL server, Cirrus Link’s MQTT Engine as well as the Alarm Notification Module and Twilio Notification Module.

In the field, cellular transmitters called Rangers from Signal-Fire are used to post discrete analog process values to EOSi’s MQTT broker in Ignition. IIoT gateways from Moxa with “Ignition Onboard” pull and push, where appropriate, other data points from memory space shared between the Gateway and the customer’s PLC network. The Moxa devices have full firewalls, are accessible via VPN only, and have physically separate NIC cards to ensure there is no active connection between the subnet that the customer’s PLCs are on and the network subnet used internally by the MQTT Gateway, nor the third cellular network. The MQTT protocol transmits tiny amounts of non-contextual numerical data on this third cellular connection, which is also encrypted and linked to CA certificates, so interception or hacking is not a concern.

Functionally, through the magic of MQTT, live process values appear in the Ignition tags. Formulas in expression tags provide the control algorithm. The results of the algorithms are sent back down via MQTT to the IIoT Gateway and then to the local PLC for further analysis or direct control of analog outputs. With the use of templates, EOSi developed HMIs for each site or customer at very little additional cost, since the Ignition license allows unlimited users, tags, and screens.

What was concerning, at least in the beginning, was the reliability of the cloud. To that end, each interface featured a watchdog element monitored at the server level by Ignition.

Ignition – monitored from uptime.com, a third-party service.

• Site PLC communication – a heartbeat value from the PLC ensured site communication was functional.
• IIoT Gateway to Ignition – additional heartbeat value ensured communication between the on-site IIoT Gateway and Ignition.
• Ignition to SQL database – internal checks monitor this connection.
• If any of the above watchdogs fail, notifications (email or SMS text) configured with Twilio notify plant operators and EOSi personnel.

Results:

After four years of production installations, the only communication failure has been between the site PLC and local IIoT Gateway. In each case, after contacting the customer, the issue was identified to be a power failure at the PLC, sometimes intentional due to maintenance or sometimes a local power outage. In one case, EOSi notified the site before they had noticed it themselves. It is worth noting that because these watchdogs are monitored in the cloud, they are always active, regardless of local conditions. In other words, when the application is appropriate, EOSi has found this methodology to be more reliable than locally installed PCs and PLCs.

EOSi has moved from the traditional full-blown PLC cabinet to a very small box and reduced the cost by almost two orders of magnitude. As a business model, this cost reduction has allowed them to go from the tedious process of bids, submittals, and “hurry-up-and-wait” PLC cabinet installations to one where they can provide their cloud-based control system at no additional charge as long as the customer is buying MicroC products.

For EOSi, the Ignition platform has been life-changing for day-to-day business. Their usual deliverable is a small electrical enclosure containing the communication gateway and power supply. The most minimal footprint of all was their latest installation, where EOSi simply mailed a $800 Gateway to a friendly on-site controls electrician – the customer snapped it onto an inch of DIN rail in an existing PLC cabinet, wired some power to it, and plugged in the Ethernet cable. EOSi had configured the gateway before it left, and everything was up and running in hours, not days.

Start Date: December 2019

Deploy Date: Ongoing