Applying Apps in Industrial Automation | Automation.com

Applying Apps in Industrial Automation

Applying Apps in Industrial Automation

By Don Pham, Sr. Product Marketing Manager at IDEC

In our daily activities, we prefer to use an app instead of browser-based access. For example, it’s possible to connect to a search site, type in the word “Maps,” and open up the corresponding web-based application to find directions. Instead, most people have a navigation app installed on their phone, and they simply click on it to find their way.

Apps are preferred over browser-based access because they are faster to access, quicker to open, work better with low latency connections, and are faster and easier for interactions. This is because they are custom designed to perform only one task and do it well, as compared to a web-based connection which must stand ready to provide access an enormous range of applications spanning the internet.

For industrial applications, apps have an even more pronounced advantage over browser-based access because speed of interaction is generally more important in the industrial world than in the consumer arena.

For example, app access is often used in the industrial world to replace a local human machine interface (HMI) interfacing to a PLC. If the local HMI used pushbuttons, indicating lights and digital meters it was extremely fast to react, with a push of a button reflected near instantaneously with a change in the status of a light.

If the local HMI was a graphics panel, such as depicted in Figure 1, interaction was not as fast, but still very quick. Users therefore expect interactions with PLCs via their smartphones or tablets to be as quick as possible, an area where apps have a pronounced advantage over browser-based access.

Users need the quick interaction provided by apps, and they also need an app used as an HMI for a PLC to provide much of the same functionality as a graphics panel.

Figure 1, HGIG: Panel-mount HMIs like this IDEC HG1G are increasingly being replaced or supplemented by smartphone and tablet apps for interface to PLCs.

 

Apps Replace and Supplement Panel-Mounted HMIs

Machines typically found in a plant or a facility are usually controlled by a PLC, with a local HMI providing interactions with the PLC and local operator interface. For plants or facilities with many machines, it often doesn’t make sense for each to have its own full-featured HMI because this adds costs, takes up space, and increases the need for spares and maintenance.

Instead, smaller machines and those not requiring constant operator interaction can be supplied with just a few pushbuttons and lights, with all other HMI functionality provided by an app running on a smartphone or tablet. For machines requiring a full-featured and permanently-mounted HMI, an app can be used to provide remote access, whether this access is required locally to the plant, or many miles away.

In either case, the app needs to provide functionality similar to an HMI, with the capabilities listed in the Table.

Table, Required App Functionality for PLC Interface and HMI

  • Runs on any iOS or Android mobile device
  • Provides a range of wireless connectivity options
  • Updates PLC firmware
  • Downloads and uploads PLC programs
  • Includes role-based access
  • Monitors PLC parameters
  • Changes PLC setpoints and other values
  • Extracts stored data from the PLC
  • Sends data via text or email
  • Sends data to the cloud

Let’s look at each of these required functions in more detail to see just what modern apps can offer to users, using IDEC’s WindEDIT Lite app as an example.

 

Connectivity Comes First

The app must first be downloaded, and it should be compatible with any iOS or Android mobile device, typically a smartphone or tablet. The app should be free or very low cost because it will typically be downloaded to many mobile devices.

Nothing happens between an app and a PLC until connectivity is first established. The app should interface to the vendor’s family of PLCs via wireless Bluetooth or Wi-Fi Ethernet for two-way local or remote access. Bluetooth is an ideal solution for local, limited-range connections where an Ethernet network may not be available, such as within an industrial plant or facility. Wi-Fi has more range and can be used for communications over longer distances.

Because the connection between the mobile device and the PLC is wireless, users never have to worry about having the right cable or the latest programming software to download or upload a PLC user program, as these tasks can be accomplished with the app. Users can also update the PLC to the latest firmware. Without an app, these types of tasks typically required a laptop PC and the right cable, and required the users to open a cabinet door and plug the cable into the PLC.

Security is a must for these types of apps, so all access should be role-based, meaning access should be able to be configured in the PLC for each user. Each app user is required to provide his or her correct username and password or access will be denied. Read/Write protection should be configurable for each designated user, allowing restricted access based on the user’s needs; for example, only read and no write privileges.

Once secure connectivity is established, users can execute the main tasks required for these types of apps: interface to the PLC.

 

App-PLC Interface

The app should allow the user to monitor any PLC parameter, and to change set points and other values. Data register, input, output, timer, counter and other commonly used values should be quickly accessible via a built-in dialog interface (Figure 2). The app should also have custom dialog interfaces which the user can configure to allow only certain PLC parameters to be monitored and controlled. Trending should be supported within the app, with users able to plot multiple register points for graphical views (Figure 3). As previously mentioned, the app should also allow the user to download and upload PLC user programs.

Figure 2, App Dialog Interface: Built-in dialog interfaces on this IDEC WindEdit Lite app allows users to quickly access different features and functions.

Many PLCs have the ability to log data to onboard memory or to an SD card. The app should provide the ability to view this logged data in a variety of formats, from text-based to trends. The app should also be able to send this logged data to one or more recipients as an attachment via a text message or an email.

Users should also be able to push logged data to a local or cloud-based database, or to a data storage platform such as Dropbox, Google Drive, Apple iCloud, etc. In addition to logged data, the app should be able to send and retrieve other data such as user programs, firmware and recipes to and from databases and storage platforms.

Figure 3, App Trending: IDEC’s WindEdit Lite app supports trending of PLC variables, allowing users to view current and anticipated future conditions.

Here are a few examples of how these types of apps can be used.

 

Application Examples

An OEM machine builder sold its equipment to a customer, who needed to make a minor modification to the PLC program to accommodate a change in its production process.

The OEM made the PLC program modification and sent it to the customer via email. The customer opened the email on his iPhone, and used IDEC’s WindEDIT Lite app to download the updated program to an IDEC MicroSmart FC6A PLC via a Bluetooth connection.

In another application, a plant operator needed to send production status to the plant manager at the end of a shift, and to store this data in a historian.

The operator used the WindEDIT Lite app installed on his Android tablet to retrieve the logged data from the MicroSmart FC6A PLC via Bluetooth. He then attached this logged data to an email, which he forwarded to the plant manager via Wi-Fi. He also sent the logged data to a cloud-based historian, also via Wi-Fi.

Figure 4, MicroSmart FC6A Plus PLC: Data logging to onboard memory or to an SD card is supported by IDEC’s MicroSmart FC6A PLCs, and this logged data can be accessed by IDEC’s WindEdit Lite app.

 

Conclusion

With all the advantages they provide over browser-based access, why aren’t apps more widely available from vendors? The main reason is because apps are expensive to develop and maintain as compared to browser-based access.

Each app must be designed to work with a particular family of a vendor’s products, such as a group of PLCs. It must also be continually updated to keep up with any changes in the PLC firmware, and any changes to the iOS and Android operating systems.

This extra level of effort required from vendors is the primary reason why not all PLCs can be accessed via an app. But when vendors do choose to go the extra mile and provide app access to their PLCs, especially when the app is free, users benefit in many ways.

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