Subject: Assistance Needed with Micrologix 1400 Series B and HART Data Retrieval Hello, I’m seeking guidance regarding my Micrologix 1400 Series B PLC, which is currently installed above ground at a mining site. I need to access HART data from a flow meter located underground. We have successfully installed the Schneider STB with HART modules and confirmed that the STB module is effectively capturing all necessary data from the flow meter. However, I’m encountering difficulties in getting the PLC to retrieve this data from the STB module via Modbus TCP. I know that the ML 1400 Series B is compatible with Modbus TCP. I’ve enabled the feature in the programming and configured the message instructions accordingly. Yet, after toggling a specific bit to activate the MSG instruction, I receive an error message stating, "Local Communication is shut down?" I have verified that the Modbus TCP features are enabled. On a positive note, I can connect to the Schneider STB module remotely from the surface without any issues and make adjustments as necessary. I’ve attached two screenshots of the RSLogix MSG configuration for both the totalizer and the STB registers. Any advice or insight you can provide would be greatly appreciated. Thank you in advance for your assistance!
User Richleva noted: "After enabling the MSG instruction, I encountered the error message 'Local Communication is shut down.' Could someone provide insights on this?" Based on my experience, this error typically indicates that a power cycle of the PLC (Programmable Logic Controller) is necessary for the changes made to the Ethernet port to take effect properly. Additionally, the node number (Unit Identifier) set to 255 seems questionable. I'm not well-acquainted with your specific device, so it could be acceptable, but some devices may disregard the node number when using Modbus TCP, as they are often identified by their IP address.
According to the RA Knowledgebase, it is essential to power cycle your MicroLogix 1400 after enabling Modbus/TCP in order to successfully reset the communications stack. For more information, visit the official Rockwell Automation support page here: https://rockwellautomation.custhelp.com/app/answers/detail/a_id/117801.
Thank you, everyone! I'll give this a shot tomorrow. However, I have a question: when I download to the controller, does it automatically cycle power, or is that not the case?
User "richleva" commented: "Thank you, everyone! I plan to give this a try tomorrow. However, I'm curious—when downloading to the controller, does it automatically cycle the power? Or perhaps not…? I clicked to expand and found that a power cycle is only necessary when making adjustments to the channel settings. Simply altering the IP address may temporarily allow communication to continue, but any modifications to the port require a power cycle. I’ve also encountered the same error when enabling Modbus TCP and switching to run mode without performing a power cycle."
According to OkiePC, in my experience, encountering this issue often signifies that it’s essential to power cycle the PLC to ensure that any modifications made to the Ethernet port are applied correctly. Additionally, the use of a node number (or Unit Identifier) set to 255 raises some concerns. While I'm not well-versed with your specific device, it's worth noting that some devices may disregard the node number in Modbus TCP since they can be accessed directly via their IP address. However, I've often found that the unit ID—whether referred to as slave ID, node ID, or something else—can be quite important, even in Modbus TCP scenarios. It would be wise to double-check that you're utilizing the correct slave ID in your Modbus polling configurations.
It sounds like you're on the right track with your setup! The "Local Communication is shut down" error often comes from either a configuration issue or maybe something in the PLC's communication settings. I’d recommend double-checking your MSG instruction parameters against both the STB module and the flow meter's specs. Additionally, ensure that the protocol settings match, especially the baud rate and data bits, since any mismatch there could lead to connectivity issues. If you haven't already, try power cycling the PLC and the STB module after making any changes to ensure everything refreshes properly. Sometimes a fresh start can clear up those stubborn communication hiccups. Good luck!
It sounds like you're quite close to getting everything set up with your Micrologix 1400 and the Schneider STB. The error message "Local Communication is shut down" usually indicates that there might be a configuration issue or that the PLC isn't fully recognizing the communication path. First, double-check that your Modbus configuration matches the expected settings on the STB module, especially the IP address and port. Additionally, ensure that the MSG instruction you set up is properly configured for both the source and destination data types; sometimes a mismatch here can cause retrieval issues. If nothing seems to be working, consider resetting the communication parameters or rebooting the PLC; it might help clear any hiccups in the connection. Good luck, and let us know how it goes!
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Answer: - Ensure that the Modbus address and register settings in the MSG instruction match those on the STB
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