HMI & PLC Troubleshooting: What Is It & How Does It Work?
When an HMI stops talking to its PLCs, production stalls. Common causes of communication failures, and how engineers approach HMI and PLC troubleshooting.
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Human-machine interfaces (HMIs) allow workers to operate machinery precisely and effectively. When the HMI works properly and communicates with the system’s programmable logic controllers (PLCs), the overall experience is efficient and user-friendly.
But what can you do when your HMI and PLCs stop communicating with one another? Dreiym Engineering’s guide to HMI and PLC troubleshooting aims to provide information about what this system is and how it works.
Failure To Communicate
When your HMI is no longer connected to your system’s various PLCs, it cannot give commands to those controllers that keep your automated system running. For workers, this means it’s harder to know the machine’s status and difficult to predict failures without that machine communication in place.
Troubleshooting Intermittent Failures
If your HMI and PLCs are connected via Ethernet, an electrical engineer may be able to perform PLC troubleshooting by running simple ping commands from both ends of the circuit. Common culprits for intermittent failures include loose connections at the terminals and data transmission concerns with your software.
If it is a software problem, you may have duplicate IP addresses within your subnetwork that are interfering with communication. Many engineers use data packet sniffers to look for hiccups like this in your software.
Troubleshooting Unresponsive Systems
If your consulting engineer has performed ping requests that turn up totally unresponsive, you may have deeper concerns with your wiring. The engineer will perform a visual inspection of the relevant cables and recommend replacing any frayed or otherwise damaged wiring components. A quick way to check for invisible damage is to replace the cable connecting the HMI and PLC with one that they know works well.
Total lack of response in your system may also require a second look at your firewall. If you have recently updated your system, your software may have changed some firewall rules automatically. Going back into the firewall and updating permissions for your HMI’s TCP/IP port should restore communication.
Automated electrical systems require all components to be in constant communication with one another. If that line of communication is dropped for some reason, enlist a consulting engineer to perform HMI and PLC troubleshooting. This guide from Dreiym Engineering provides foundational knowledge of what it is and how it works so you know what to expect when the engineer arrives.