I possess an AB 1769 L18ER PLC connected to our plant network through a NAT device RAM 6021. Recently, the connection to our Ignition SCADA system has been experiencing disruptions. The device's connection status would frequently switch from connected to Idle, causing the tags to become unreadable. Despite still being able to locate it on RSLinx and attempt to access the controller online, I was unable to connect using its NAT'd IP address. This issue persisted until I relocated the PLC and NAT device to a different building with a matching VLAN, where everything functioned properly. It appears that the problem lies in the network connection at the original location. I am curious about the root cause of this sudden occurrence and how to address it with our IT team, who are unfamiliar with PLCs and automation. Your insights and guidance on resolving this issue would be greatly appreciated. Sincerely, Alex
To determine if the IP address is still functioning, disconnect the NAT from the public network. It is possible that another device has been connected using the same public IP address.
Upon disconnecting my NAT, I confirmed that there were no established connections at the specified address.
Hi Alex, Based on your description, it indeed seems like a network-related problem rather than an issue with the PLC itself. My initial thought is that there might be some network congestion, a physical fault, or some firewall settings in place in your original building causing this disruption. Also, the fact that everything works properly after shifting to a new location with a matching VLAN adds more weight to this hypothesis. You could try getting your IT team to perform a thorough network analysis at the original location. A good place to start would be to check for potential packet loss over the network and evaluate bandwidth usage during instances of disconnection. Request them to look into the physical integrity of all the networking hardware involved and possibly scrutinize the firewall / security settings to ensure they're not interfering with the connection. Make sure you explain the problem in terms they'd be familiar with - intermittent connectivity loss, unreadable data packets, etc. Hope this helps! Best, John
Hey Alex, it sounds like you've done quite a bit of troubleshooting so far. From what you've described, it seems like the issues might be originating from a network problem at the initial location, rather than a hardware issue with the PLC or NAT device. Network issues could be causing packets to drop, which might go unnoticed in day-to-day work but could cause SCADA connections to fail. I'd recommend monitoring the network traffic in the problematic area using network diagnostic tools. Look for anything suspicious, like unusually high traffic or sporadic losses of connection. If you do find an issue there, you should be able to present this data to the IT team, who, while they might not be familiar with PLCs, should know how to approach network problems. Remember, good communication between your side and IT can be a huge help in resolving such issues.
Hey Alex, it sounds like a tricky situation but you've done great with the troubleshooting so far. I agree that the issue seems network-related, considering the problems disappeared when you moved the setup to a different network. One thing you could check is whether there have been any recent changes or updates to the network settings or firewall rules at the original location. Something might have inadvertently affected the connectivity of your PLC. When explaining the situation to your IT team, stress that the device worked perfectly on a different VLAN which indicates a networking problem. They might need to review their switch configuration or perhaps work with you on setting up QoS for your PLC's data.
Hi Alex, it sounds like you really nailed down the problem by relocating the PLC and NAT device! The disruptions you experienced could be due to various factors like network congestion, misconfigured VLAN settings, or even issues with the NAT device itself. It might help to involve your IT team in checking the network performance, inspecting the router and switch configurations at the original site, and ensuring that the right ports for SCADA communication are open and prioritized. Sometimes, even a slight change in network traffic can lead to unpredictable behaviors with industrial devices, so monitoring historical data for any spikes or drops in usage could provide more context. Good luck with your troubleshooting!
Hey Alex, it sounds like you’ve run into a frustrating issue! Since the connection stabilized after moving the PLC and NAT device, it’s likely that there was a problem with the network configuration or physical infrastructure at the original location, like faulty cabling, switches, or even VLAN settings that weren’t properly aligned. It might help to share this experience with your IT team and get them to check for any network interruptions, packet loss, or misconfigurations on the original VLAN. Sometimes, doing a thorough network audit can uncover hidden issues. Good luck, and I hope you get this resolved smoothly!
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Answer: - The disruptions in connection could be caused by network issues at the original location, such as network configuration, interference, or connectivity problems.
Answer: - To troubleshoot connectivity issues, you can start by checking the network configuration, ensuring proper IP addressing, verifying network stability, and testing connectivity using tools like RSLinx.
Answer: - Relocating the PLC and NAT device to a different building with a matching VLAN is a temporary solution, but working with the IT team to investigate and resolve network issues at the original location is essential for a permanent fix.
Answer: - It's important to communicate the issue in non-technical terms, highlighting the impact on operations and the need for IT support to investigate network connectivity problems affecting the PLC and SCADA system.
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