Is access to your data frictionless?

In this installment of Automation Zone, learn how to find the right tech solution for securely accessing data.

By Benson Hougland, Opto 22

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Industrial plants and facilities often produce big data, which can be distributed and analyzed to improve operations and maintenance and to reduce repair costs. But securely getting this data to the people who need it can be complex. Many options are available, including:

  • In-house systems
  • Virtual private networks (VPNs)
  • Cloud for data transmission only
  • Cloud for hosting end-user or vendor systems

Before exploring these options, let’s examine characteristics common to all. Big data is generated by wired and wireless sensors, transmitters and analyzers installed in plants and facilities. These field devices acquire data and typically connect to inputs of industrial controllers, such as programmable logic controllers (PLCs), programmable automation controllers (PACs) and edge programmable industrial controllers, or EPICs (see Figure 1).

Industrial controllers not only obtain raw data from field devices, but also they process it to filter out anomalies and analyze it to derive more useful information. Most industrial controllers have some data storage capacity built in, but it’s common to connect these controllers—either directly or through HMI software—to PC-based software platforms. These platforms may be data historians for storing large amounts of data or other database types.

Knowing how big data is initially acquired and processed, let’s look at options for accessing it.

In-house systems

With this option, a plantwide intranet connects each user’s PC, and a plantwide Wi-Fi network may also connect laptops, smartphones, and tablets. The plant’s information technology (IT) personnel usually provide the required infrastructure, including PCs, networking hardware, software platforms, and so on.

In-house systems are often the best approach for companies with just a single plant or facility. This is particularly the case when support for plant operations is provided exclusively by in-house personnel.

Although this option appears simple, it requires IT staff for installation and support, and it does not provide data access for personnel outside the plant. Also, while IT teams are well-suited for administering the networking and data storage infrastructure, they are often far less familiar with specific operations technology (OT) software, protocols, and process historians. An in-house system therefore requires close cooperation between IT and OT personnel.


VPNs are an established and secure technology frequently employed by IT personnel to interconnect remote locations over public networks, such as the internet. This method lends itself well to big-data storage and access applications, particularly for very large files, such as videos.

When data access is required by personnel outside the plant, VPNs are often used to extend the plant’s in-house network. VPN solutions do carry some of the same downsides as in-house systems, and they present additional challenges as well.

Both the local and remote ends of each VPN link must be coordinated and maintained by IT, which may be logistically challenging. Furthermore, configuring and maintaining a VPN can be quite complex, both initially and throughout the life of the system.

Cloud for data transmission only

Using the cloud for data transmission offloads IT-related tasks, allowing plant OT personnel to focus on improving operations (Figure 2). This is made possible by using open protocols optimized for exactly these kinds of data transfers.

For instance, message queuing telemetry transport (MQTT) is an ISO standard (ISO/IEC PRF 20922) publish-subscribe messaging protocol. MQTT is ideal for industrial data gathering because it is lightweight and efficient and because it securely transfers data even with slow or unreliable networks.

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