How I fell in love with the cloud
From the early days of PLC systems, DCS and distributed instrumentation, the need for data monitoring in centralised control rooms was apparent. Remote monitoring and general remote access to sites followed soon thereafter by all users.
Remote access was mainly driven by system integrators who needed to provide technical support, which was rapidly followed by project managers and production supervisors. For the first few years, access was provided (and still is) by PC-based software remote access utilities. Later, when the web interface evolved, software developers started adding remote desktop connectivity and web-server functionality as add-on options to the PC-based SCADA software station servers. Access by remote operators and authorised users suddenly became even simpler.
SCADA software - with its GUI interface, data monitoring, data logging, alarming and reporting - has been, and still is, notoriously expensive. In order to set up a multistation SCADA network with on-site and off-site access, the user needs to add extra licences to the existing SCADA server station - and that’s in addition to adding multiple PCs and operating systems. Such a solution can rapidly become commercially prohibitive, especially for small to medium-sized projects.
Back in 2009, being a veteran of many years of SCADA and telemetry systems, I was listening to a presentation discussing data monitoring utilising the internet as a new paradigm for SCADA monitoring. The new service was referred to as SCADA in the ‘cloud’.
My first reaction was: Why on Earth would anyone wish to display or upload their system’s data to a website which is physically not installed on-site? How secured can a cloud-based website be? What is actually required to achieve all that the cloud is promising? How robust is the concept and how are clients going to pay for the service?
For a while, I was still contemplating the benefits and the potential risks involved in using a central SCADA monitoring station, which in reality is not here ‘on Earth’ but rather elsewhere in the cloud. My initial hesitations came slowly to a halt when I was asked to set up a system to remotely monitor, alarm and report on a medium site which included multiple refrigerators and deep freezers. Access was to be given to multiple users from anywhere in the world at any time. The total number of sensors was not more than 50. I have decided to try this new approach in SCADA by implementing cloud monitoring, which offered a direct data link to a secured website to multiple users at no extra cost.
Enter ‘the cloud controller’
A ZigSense cloud controller combines multiple hardware and software features in a relatively low-cost system. It includes few built-in I/Os (analog and digital); a built-in Modbus RTU serial port for interface to external systems such as PLCs, other data loggers and smart controllers (temp, flow); and an optional short-range wireless RF extender port to remote wireless I/Os.
The main point to remember is that the controller’s ability to upload its sampled I/O data to a secured website will be called, from now-on, ‘ZigCloud’. To achieve robust upload routes, the cloud controller includes two communications channels: an ethernet port and a built-in 3G modem that requires a cellular network SIM card. The two communications channels are backing up each other to ensure data is not lost as it travels to the cloud.
A data logging functionality is built into each controller. Local data logging is activated when both uplink communication channels are lost, ensuring no monitored data is lost.
From Earth to the cloud and back
Once data generated on Earth arrives at the cloud, it is recorded according to the data logging settings defined by an authorised user. Sampled data can also be viewed using standard built-in cloud GUI ‘widgets’. Widgets resemble SCADA software GUI objects, eg, gauges, bar graphs, charts and tables.
Alarm conditions will generate and send alert messages in the form of SMSs, emails, tweets and voice messages. Should the project require additional programming capability, a powerful ‘C’-style script language is built in as standard and is accessible in the cloud.
By now it is clear that all the settings associated with the I/Os, alarms, graphical interface and statistical reports are all done in the cloud and the user only requires access to a standard web browser, available anywhere. To access the cloud, no PLC or SCADA software is required, there is no PC hardware or operating system to deal with and there is no network to set up. Everything you need to set up a multi I/O monitoring system is achievable in the cloud via the browsers.
Security, security and more security
All communications to/from the cloud controller must go through the data centre servers. The cloud itself is supported by multiple data centres continuously backing up each other. The cloud servers are exclusively dedicated to cloud controller communications and are not used for any other email/web or non-controller-related applications. Each server is located behind a firewall and only the necessary ports are opened for communication. Management of the servers is only made available to the data centre server owner.
The cloud controller strictly uses UDP traffic to communicate with the servers. Each message is fully 128-bit encrypted. When data arrives at the cloud controller after being sent by the data centre, the controller will run multiple security checks on the decrypted data and will only accept the data if it has passed all tests; otherwise, the data will be dropped. This means that only genuine traffic from the server will be accepted and any other traffic will be ignored. We can conclude that the cloud controller poses no risk to any network and there is no way to load any other software into its memory.
Using the cloud for remote data monitoring and control functionality provides a suitable tool for small to medium-sized SCADA applications.
The main advantage of using the cloud for SCADA applications is its low price tag when compared to the price of SCADA software, PC-based servers and operating systems. The cloud enables authorised employees and programmers to be anywhere, in any time zone. Management can now outsource work to highly specialised contractors while maintaining a handle on the project at all times.
Last but not least, by reducing the need to travel to site the cloud saves on energy and carbon footprint.
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