I manage a network consisting of 17 1734-AENTs, but one AENT consistently experiences communication issues. The AENTModule Status shows green, with Network Activity rapidly flashing green, Network Status and Point Bus Status both flashing red, and I/O Module Status showing green while Network Status flashes red. Despite trying various solutions such as replacing the ethernet cable, adjusting the RPI to 250ms, ensuring the cable is isolated in a conduit away from AC sources, and even swapping modules, the problem persists. Restarting the AENT temporarily resolves the issue, ruling out an IP conflict due to the inability to ping the node when it goes offline. Before resorting to Wireshark for further investigation, I am seeking additional suggestions on troubleshooting steps. Additionally, I am looking for recommended resources such as videos or blogs to guide me through using Wireshark to troubleshoot an AB network, as I am a novice in this area.
Is a power surge the culprit? Are you able to switch out the power supply responsible for the module in question?
When adding a new adapter in Logix, the default scan time is set to 20ms, which can be too aggressive for networks with unmanaged switches or lower speeds. It is recommended to adjust the scan time to 50-100ms for better performance. In cases of high-speed activities, setting up Quality of Service (QOS) to prioritize the unit is essential.
Have you reviewed the statistics for the PLC Ethernet module web page? What baud rate is configured on your AENT? It is recommended to keep it at Auto Negotiate unless there is a specific reason to change it, such as for DLR functionality.
What are the different types of modules and how many are typically found in a chassis?
Troubleshooting I/O Timeout on 1734-AENT Module - Resolve with Power Cycle When the Network Status and Point Bus Status LEDs on your 1734-AENT module are both flashing red, it indicates a timeout in the I/O connections from the controller. To mimic this issue, simply disconnect the PLC from the network. If pinging the node is unsuccessful when it goes down, it is unlikely due to an IP conflict. In the event of an IP conflict, the Network Status LED on the 1734-AENT module would remain solid red. However, if it's a temporary I/O timeout caused by noise or loss of connectivity to the ControlLogix, the IP stack should still be functional for PING, HTTP, and RSLinx. Consider the physical setup between the ControlLogix and the troubled 1734-AENT module. Verify if the malfunctioning device is the only one connected to the switch used for network connectivity. When diagnosing with PING after a failure, note the switch you are connected to and the physical path to the 1734-AENT module. If power cycling the AENT module resolves the issue, determine if only the module itself is being cycled or if the entire enclosure is affected. It's important to ascertain if the connected switch also undergoes a power cycle. Observing the Network Activity light flashing may indicate a good physical connection, but the inability to communicate through PING, TCPING, HTTP, or RSLinx suggests a blockage or unavailability of access to the Ethernet port from the network.
It seems like you've taken a comprehensive approach to troubleshooting so far. One thing you may consider is to check the firmware version of the problematic 1734-AENT and ensure it's up-to-date. Sometimes, issues like these can be tied to needing a firmware update. Double-check the switch configuration, as well - issues can arise if IGMP snooping or querier is not properly configured with EtherNet/IP devices. As for learning Wireshark, it's a great tool once you get the hang of it. I can suggest a couple of resources for you. "Laura's Lab Kit v11", a set of three books, is an excellent detailed guide to mastering Wireshark. On YouTube, the channel "Hak5" covers many Wireshark basics in their network hacking series. Good luck with your troubleshooting attempts!
It sounds like you've already taken several appropriate troubleshooting steps, but it seems strange that the problem persists despite module swapping. Have you considered that the issue might be related to the network switch involved or even potentially the module's slot in the rack? It might be worth trying to connect this problematic AENT to a different port in your switch, or to a different switch altogether, to rule out any hardware issues on that front. If the problem isn't with the network switch, try a different slot in the rack, in case there's a backplane issue. As for resources on using Wireshark to troubleshoot an AB network, I recommend YouTube tutorials, particularly those by "PacketBomb" - they're thorough and beginner-friendly.
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Answer: - Answer: There could be various reasons for persistent communication issues, including hardware faults, network configuration errors, or interference. Further investigation using tools like Wireshark may help uncover the root cause.
Answer: - Answer: In addition to the steps you have already taken, such as cable replacement and adjusting RPI, utilizing network diagnostic tools like Wireshark can provide detailed insights into network traffic and potential issues.
Answer: - Answer: To learn how to use Wireshark effectively for troubleshooting an Allen-Bradley network, you can refer to online videos, blogs, or tutorials that provide step-by-step guidance on capturing and analyzing network traffic specific to your setup.
Answer: - Answer: Temporary resolution by restarting the AENT module could indicate a potential software glitch, transient network issue, or internal module reset that clears the communication problem temporarily. Further investigation is recommended to identify the underlying cause.
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