From SCADA software to cloud-based monitoring

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 web interfaces evolved, software developers started adding remote desktop (RDP) connectivity and web-server functionality as add-on options to the PC-based SCADA software 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 etc. 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 alarms 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 then 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 for multiple users at no extra cost.

Enter the cloud controller

A ZigSense cloud controller combines multiple hardware and software features into 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, 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 servers.

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-site arrives at the cloud server, 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. The widgets resemble SCADA software GUI objects such as gauges, bar graphs, charts and tables.

Alarm conditions will generate and send alert messages in the form of SMS, email, Twitter 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 (aka SCADA tags), 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 server no PLC or SCADA software is required, no PC hardware or any operating systems to deal with and no network to set up. Everything you need to set up a multi-I/O monitoring system is achievable in the cloud via a browser.

Security

All communications to and 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 uses UDP traffic to communicate with the servers and 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.

Summary

Using the cloud for remote data monitoring and control functionality provides a unique solutions 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 reduces carbon footprint.