Top 10 Programmable Logic Controller Monitoring Tools

PLCs are such crucial devices that they gave rise to a whole industry dedicated to supporting them, including PLC monitoring tools that can ensure they are working correctly and alert in case of failures. In this article, we will present some of the best options available and hope to help you choose the best one for your needs.

• FAQ’s about PLC monitoring
• The best PLC Monitoring tools
  • PRTG, Ixon, CNCNetPDM, Zabbix, Modbus Monitor, PLC Analyzer Pro, MachineMetrics, AnyViz, Bridgera Monitoring, DataDog
• Conclusion

Programmable Logic Controllers (PLCs) are industrial computers used for the monitoring and control of manufacturing processes, including environmental and machine sensors, assembly lines, industrial robots, and much more.

Developed for General Motors in 1968 to replace earlier, analog and hard-wired automation systems, PLCs gained popularity due to better reliability, expandability, and easier and more flexible programming, allowing for quick iterations of manufacturing processes and better tailoring to specific needs.

Over the past 50 years, PLCs established themselves at the heart of industrial operations worldwide, and became important components of larger trends like Machine to Machine (M2M) communication and the Industrial Internet of Things (IIoT), which themselves are part of what we call the “fourth industrial revolution” or “Industry 4.0”.

Frequently Asked Questions About Programmable Logic Controller Monitoring

What are Programmable Logic Controller monitors?

Programmable Logic Controller monitors are tools that can be used to monitor the status, health, and performance of PLCs in your industrial infrastructure. They can vary in complexity, from simple tools that report raw values received from your PLCs to more sophisticated ones that include features such as historical data analysis, performance baselining, or device management.

Keep in mind that many Programmable Logic Controllers may not be able to communicate using modern interfaces and protocols like Ethernet, USB, or TCP/IP. To remotely monitor these, you will need a hardware device acting like a gateway, which communicates with your PLCs using legacy interfaces (like serial) and protocols, gathers information, and forward them to a cloud service.

In fact, some of the solutions mentioned in this article are available as a package deal, where you buy the hardware and get access to the software platform. It is up to you to determine if this extra hardware is needed, and to factor the cost of this hardware when making a purchasing decision.

Why Should You Invest in Programmable Logic Controller Monitoring?

There are many reasons to invest in Programmable Logic Controller monitoring. Here are five of them, in no particular order.

1. Performance optimization: continuous monitoring can help you pinpoint issues and identify opportunities for optimization that will improve the productivity of your Programmable Logic Controller infrastructure, sometimes without the need for hardware upgrades.

2. Security: monitoring allows you to spot early signs of uncommon behavior or usage patterns indicative of an intrusion attempt or ongoing attack. This will give you time to react and deploy countermeasures before a data breach occurs.

3. Resource allocation: find out where resources are being underutilized or overutilized, allowing you to redistribute them according to real needs to ensure the most effective usage of your systems.

4. Proactive maintenance: monitoring allows you to detect and fix potential issues before they become critical and result in outages that may affect the productivity of your infrastructure or even the profitability of your business.

5. Regulatory compliance: many businesses need to meet strict regulatory standards related to industrial processes. Monitoring will allow you to prove compliance with these standards and secure regulatory approvals that may be crucial to keep your business running.

What to Look for When Choosing Programmable Logic Controller Monitoring Tools?

Broadly speaking, there are 5 main features you need to look out for when choosing Programmable Logic Controller monitoring tools. Keep in mind that this may vary according to your specific needs.

• The capability to monitor many aspects of your Programmable Logic Controllers, and associated infrastructure, at once.
• A centralized display of information from many sensors for better observability.
• Customizable alerts and automated notifications when alerts are triggered.
• Native and automated reporting features, so you can keep co-workers and management “in the loop”.
• A free trial period, so you can attest to how the tool works with your network infrastructure.

How to do Programmable Logic Controller monitoring?

There are many Programmable Logic Controller monitoring tools, from as many different vendors, which may focus solely on a single aspect of the task or offer this capability as a subset of a broader range of features. We present a few of them below, in no particular order.

The Best Programmable Logic Controller Monitoring Tools

PRTG, Ixon, CNCNetPDM, Zabbix, Modbus Monitor, PLC Analyzer Pro,

MachineMetrics, AnyViz, Bridgera Monitoring, DataDog

PRTG

Paessler PRTG is the Swiss army knife of the monitoring world. PRTG is based on basic monitoring elements called “sensors”. One sensor usually monitors one measured value in your network, e.g. the traffic of a switch port, the CPU load of a server, the free space of a disk drive, and so on.

With more than 250 built-in sensors for various tasks, device types, and use cases, you would be hard-pressed to find something you can’t monitor with PRTG. Plus, you can mix and match sensors, and even deploy custom ones, to create monitoring solutions specific to your needs.

PRTG includes sensors for two of the most common communication protocols used by PLCs: Modbus TCP, with data transferred over TCP/IP networks, and Modbus RTU, commonly used on serial communication. Both give you access to all the register, value, and data types specified by the protocol. There are also sensors for the MQTT protocol, commonly used on IoT devices and supported by some PLCs. 

The information gathered by PRTG is shown on a centralized dashboard with all the relevant metrics. You can set alerts based on threshold values, with notifications delivered by text (SMS) or email if those values are exceeded. There is also an automatic reporting feature, so you can keep management and co-workers informed.

PRTG is available on a perpetual license basis, which means that after you acquire a license, there are no recurring subscription costs. It runs on Windows Server 2012 R2, 2016, 2019, 2022, or Windows 11. There is a 30-day free trial of PRTG, with all features available during this period, no credit card is needed.

IXON Cloud Platform

The IXON Cloud Platform is a fully cloud-managed IoT and IIoT solution, which claims to eliminate the need to have people on-premises for tasks such as device configuration, updates, and user management, allowing you to manage your whole fleet from a single location and a user-friendly interface.

Data can be collected from PLC devices based on a time interval, change of status, or specific trigger (ex: when a value is exceeded), and transferred to the cloud over a secure connection. The platform allows access to both historical and real-time data, giving you an insight into past behavior and up-to-date information on the current status.

The IXON Studio is a no-code, drag & drop editor which allows for the creation of custom dashboards and visualizations, which can be personalized for different users and roles. And for those who need something truly unique, a fully-documented REST API allows for the integration of all the features of the platform into custom applications.

The IXON Cloud Platform is SaaS (Software as a Service) and available in two plans: Standard and Enterprise. The Standard plan is free for users of the IXRouter VPN router & edge gateway devices, which collect data from PLCs and industrial devices and forward them to the cloud.

CNCNetPDM

CNCNetPDM serves as a “middleman”, collecting data from your PLCs using their native communication interfaces (like Ethernet, serial, Bluetooth, USB, or manufacturer-specific buses) and translating it into a “homogenous” format that can be ingested by your applications.

The benefit of this approach is that, if you have a heterogeneous fleet composed of devices for multiple purposes and from multiple manufacturers, you won’t have to worry about the particulars of each device to ensure successful monitoring.

Data collected can then be fed to your existing MES/ERP (Manufacturing Execution Planning/Enterprise Resouce Planning) system.  The communication with devices is two-way: you can also control your devices by sending standardized commands to the tool, which are then translated to device-specific commands. M2M communication is also supported: the output of one device can be converted to a suitable input for another device.

CNCNetPDM is a software application that runs on “all Microsoft Windows Operating Systems from XP SP2 to Server 2019 or Windows 11”. For data storage, the supported databases are Oracle 11g to 12c, Microsoft SQL Server 2008 thru 2019, or MySQL and MariaDB (versions 5.5 or later). There are many licensing options, but a free tier is available.

Zabbix

Zabbix is a free and Open Source monitoring package that can do a lot, including server, cloud, application, services, and network monitoring into one tool. And it is modular, with many available plugins that add new functionality.

One of those is the Modbus plugin, which lets you monitor devices compatible with the Modbus RTU (Remote Terminal Unit, usually connected to other devices via serial interfaces)  and Modbus TCP versions of the Modbus protocol. Once ingested, the information collected from your PLCs is treated as any other data source: it can be processed in the same ways, and visualized in the same dashboards.

Zabbix has a very flexible alerting system, supporting not only SMS and email but also modern communication platforms like Slack, Microsoft Teams, Telegram, Express.ms, Rocket.chat, and more. Messages can even be customized according to the type and role of the recipient.

As said, Zabbix is Open Source and free, but you pay for the technical support. There are five support tiers (Silver, Gold, Platinum, Enterprise, and Global I), each one with different levels of availability, response times, and amount of incidents and support contacts.

Modbus Monitor

Modbus Monitor is a simple and inexpensive multi-platform application that can communicate with Modbus-enabled devices using a variety of protocols and interfaces. It can act both as a Modbus server (usually a PLC reporting data from devices connected to it) and as a client, collecting and logging data sent by the servers.

Servers can be polled manually or at specified intervals, and a timeout can be set. Data collected by the application can be filtered by user-specified criteria or exported to Comma Separated Values (.CSV) files, which can be imported into almost any spreadsheet or database available. Communication logs can also be saved.

This tool can also sniff Modbus traffic on your network and automatically build Modbus maps when clients are making requests to the server. A Modbus map is a list for an individual server device that defines what the data is and where and how it is stored. This is useful when the map is unknown or unavailable from the manufacturer.

Modbus monitor is available as apps for Windows on the Microsoft Store or Android on Google Play. The Android version is available in two versions, a free one which consists of a basic Modbus client for “beginners and explorers” and an advanced one which includes a client and a server and support for more protocols.

PLC Analyzer Pro

Developed by Autem, PLC Analyzer Pro is a software package that performs the recording and logical analysis of signals reported by the PLCs in your facilities. By using a direct connection with your PLCs and custom drivers, it can simultaneously record up to 16 million variables from 250 signal sources, making this a handy tool for failure diagnosis, cycle optimization, predictive maintenance, quality assurance, and more. 

There are some add-ons that enhance the feature set of PLC Analyzer Pro. The “Videotrack” module allows for the recording and synchronization of video feeds with sensor data, helping in the diagnosis of mechanical errors on machines.

And the Virtual HMI (Human Machine Interface) module combines a view of the status of control panels, buttons, and joysticks, with sensor data and an optional video feed from the Videotrack module to ​​help reconstruct human interactions and diagnose issues caused by operator error.

PC Analyzer Pro requires Windows 7, 8, 10, or 11, in 32 or 64-bit editions. This tool is offered in a perpetual licensing model, with pricing based on the number of workplaces and drivers needed. There is a free demo version available.

MachineMetrics

MachineMetrics is an cloud-based IIoT Platform for “modern machines”, designed to monitor and analyze the performance of your manufacturing equipment, helping you to identify bottlenecks, inefficiencies, and opportunities for improvements.

It uses hardware devices called MachineMetrics Edge to collect data from “any machine” with a sampling rate of up to 1 KHz (instead of the standard 1 Hz on many systems) and stream it securely to the cloud. It supports open protocols like MTConnect, OPC-UA, and Modbus, and also offers connectors from proprietary systems from Fanuc, Mitsubishi, Citizen, Haas, Heidenhain, and Siemens Sinumerik.

REST and GraphQL APIs allow for the integration of data stored on the MachineMetrics cloud with existing BI, workflows, reports and applications. Data can also be published directly into “Azure, AWS, SAP, and any other cloud, big data, or enterprise application”. There are also ready-to-use applications offering features like real-time dashboards, historical reporting, rules-based workflows, and text/email notifications.

AnyViz

AnyViz is a cloud-based platform that “brings the cloud to your PLC”, and allows you to monitor, operate and analyze machine and plant controls remotely. Its features include real-time visualization of data with “vizuals”, widgets that can be freely positioned on screen via drag-and-drop, giving you the freedom to design an HMI with just a few clicks.

Data can be logged and stored indefinitely. Polling can be done periodically, on “delta” (if a value changes by more than a specified amount) or on change (as soon as a change occurs). Data can be monitored for predefined conditions and alerts triggered if they are met, with delivery by e-mail, push notification, voice calls, or SMS. Besides receiving data, AnyViz can also be used to modify values on PLCs, allowing for remote control of devices from anywhere with an internet connection.

The free AnyViz CloudAdapter software transforms any device, running Linux or Windows, into an IoT gateway, with support for the most popular protocols, including OPC UA, Modbus, Siemens TCP, Beckhoff ADS, Ethernet/IP, Bacnet or MBUs. Adapter software can be updated Over the Air (OTA) and configuration is done via a web interface.

AnyViz is a SaaS platform. Sadly, the website does not make clear the service plans or pricing. Interested users can “Register for Free”, but it is not clear what features are included in this free tier.

Bridgera Monitoring

Bridgera Monitoring is an IIoT Monitoring platform that prides itself on being a “user-friendly, highly customizable industrial IoT application that companies can use to monitor their devices in real time and make data-driven decisions.”

Monitoring on Bridgera is done on customizable dashboards that show current values but also data trends. Besides showing information collected from your devices, this tool can also generate maps showing where those devices are located, leveraging known addresses or GPS information on devices equipped with this feature.

Historical data can be aggregated and custom alerts defined based on user-specified thresholds, with delivery via SMS or e-mail. A hierarchical system allows for access control by role, organization, or company, allowing your employees to see just the information they need, but nothing else.

Bridgera Monitoring is available as a web application, with versions for iOS and Android also available. Pricing and plans are not immediately available on the website. Instead, the company invites interested users to “get a free consultation”.

Datadog IoT Monitoring

Datadog IoT Monitoring provides “top-to-bottom IoT monitoring” that allows companies to have a comprehensive view of the health of their devices, as well as the ability to drill down into individual devices to troubleshoot a particular region, device type or software version, with performance and hardware metrics, logs, network data and more available in a single pane of glass.

Telemetry data is tagged, and the host map provides a bird’s-eye view of your entire IoT device fleet, grouped by any tag, for a visual comparison of performance by any criteria. Alerts, graphs, and dashboards can be scoped with user-specified tags to provide visibility and actionable notifications for any subset of devices.

Unified tagging provides a seamless correlation of issues between system-level metrics, distributed traces, network performance data, and logs. The alerting capabilities are customizable: operators can build alerts that trigger only on sustained or widespread device failures, and anomaly detection and outlier detection algorithms can automatically determine normal operating ranges and alert only on unusual occurrences.

Keep in mind that it seems there is no support for the Modbus protocol. You can, however, monitor PLCs that communicate using other IoT protocols, like MQTT. To collect data, Datadog uses lightweight agents that can run “on nearly any hardware platform and operating system”, including Linux, Windows, Android, and ARM devices. There is a 14-day free trial available.

Conclusion

Among all these, our favorite Programmable Logic Controller monitoring tool is Paessler PRTG, as it “ticks all the boxes” in our list of desired characteristics, and streamlines your workflow by enabling you to monitor all of your infrastructure with a single tool.

The built-in sensors cover many of the main use cases, without the need to purchase extras, so it can monitor your Programmable Logic Controllers, but also your network, services, servers, other IoT devices, cloud infrastructure, and much more. And it is extensible, which means you can deploy third-party sensors, or even develop your own, to cover specific needs.

That means you can do away with having to rely on a variety of individualized solutions, which can carry potential risks such as conflict with your current workflow and even network security issues. Lastly, the perpetual license model is a great way to keep your budget under control, avoiding subscription costs or surprises with extra charges if usage tiers are exceeded. Give it a try!