Hello everyone, I am currently utilizing an ABB RTU560 to establish communication with a UPS system via 2-wire RS485 serial communication. The UPS vendor has provided the necessary communication settings, specifying that the data type is integer and the function code is 3 (Holding registers). Using Modpoll software on my laptop, I am successfully able to check the data, and the RTU is polling the data without encountering any read errors. However, I am encountering an issue where the data is not updating on the RTU webserver - it only shows that the RTU is active but inoperable. If anyone can provide assistance in troubleshooting this issue, I would greatly appreciate it. Thank you in advance.
While it may seem trivial, it's important to double-check the fundamentals when dealing with RS485 wiring. Despite being labeled as a 2-wire system, it actually requires a third wire for a common ground connection. Learn more about RS485 wiring connections at Tech Schematic.
1. Does the Remote Terminal Unit (RTU) support Modbus master functionality? It is essential to confirm this feature for optimal performance. 2. The industry lacks consistency in labeling the polarity of RS-485 driver lines as either A/B or (+)/(-). While technically (+) should connect to (+) and (-) to (-), some vendors may label their drivers differently. Consider swapping the 485 connections if encountering issues with polarity labeling differences between the RTU and USB/485 converter used with Modpoll. 3. Ensure that the serial settings, including baud rate, word size (8 bits), stop bit, and parity, match on both ends for seamless communication. 4. Double-check that the RTU is polling the correct slave ID number of the UPS for accurate data retrieval. 5. The RTU must utilize FC 03 for effective communication. 6. Verify that the RTU is targeting the correct register address, accounting for potential discrepancies in addressing formats (one-based or zero-based). 7. Look for any blinking LED indicators on the 485 port to show transmission (Tx) or reception (Rx) activity. 8. Check for any error messages generated by the RTU to troubleshoot communication issues. 9. In cases of low baud rates and short distances, a 120 Ohm terminating resistor may not be necessary for proper functioning. 10. Confirm that the RTU's RS-485 port is specifically enabled for Modbus RTU communication, rather than another protocol. 11. If the RTU boasts multiple serial ports, ensure that the RTU program is directed towards the designated port for seamless connectivity.
Hi there, It sounds like you've got most of the boxes checked already since you could successfully establish communication with the UPS system, good going! Now, onto your issue, I've encountered something similar with ABB RTUs in the past. The problem could likely be either with the RTU server settings or in the specific mapping you've configured for this device. For starters, I'd suggest checking if there are any mismatches between the register address configured in the RTU vs that in UPS. Also, verify whether your RTU is correctly configured to respond via the same protocol as the UPS. If the setup seems perfect, then it might be a software issue with the RTU webserver itself. You might want to consider contacting ABB support in that case. Good luck!
It sounds like you're on the right track with the setup and polling, so that's great! For the webserver issue, it might be worth checking a couple of things: first, ensure that the RTU is configured properly to relay the data it receives from the UPS to the web server. Sometimes, there can be settings regarding data updates or refresh rates that need tweaking. Also, double-check the mapping of the data registers in the RTU’s configuration — if they’re not correctly mapped to the right holding registers, the data won’t display as expected. Lastly, look into any firmware updates for the ABB RTU560 that might address communication discrepancies. Good luck, and let us know how it goes!
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Answer: Answer: There could be several reasons for this issue, such as mismatched data types, incorrect function codes, or problems with data parsing. It is recommended to double-check the communication settings and ensure they match between the UPS system and RTU.
Answer: Answer: To troubleshoot the communication problem, you can start by verifying the physical connections, checking the communication settings, testing the communication with different devices or software, and monitoring the data flow to identify any potential issues.
Answer: Answer: In such a scenario, it is advisable to review the data polling frequency, ensure that the data is being correctly processed and displayed on the RTU webserver, and consider checking for any software or configuration issues that may be affecting the data updating process.
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