Hello everyone, I apologize for the lengthy post. As an Electrical and Electronic Engineering student who recently joined a research group, I was tasked with utilizing a PLC to control a temperature controller connected to an oven via MODBUS. The goal was to connect the PLC to a router for remote monitoring and control worldwide. Despite being new to PLCs, I successfully completed the task after much trial and error. My current assignment involves using a Delta AS218RX PLC to control and monitor an inverter via Modbus. However, I am facing difficulties as the devices operate differently. I am struggling to obtain the necessary values from the inverter. While I could easily set up communication settings for the temperature controller in hwconfig and implement a successful program, the process is proving challenging with the inverter. Initially, I attempted to read a single value (output voltage) from the inverter, but encountered issues as the value remained constant at 229V. Implementing a pulse contact resolved this issue as the value updated with each pulse. However, I am now unable to perform multiple readings. I believe I need to open and close a contact for each MODRW function in the program, but I am facing difficulties in executing this correctly. Having limited experience in PLC programming and lacking basic fundamentals, I am seeking assistance to troubleshoot the code. Any help or guidance would be greatly appreciated.
To enhance efficiency and simplicity, consider replacing the [-| |- SM407]+[-|/|- M] pairs with a single rising edge detector [-|^|- SM407]. This approach streamlines the process and improves functionality. Another option is to utilize an integer count that increments on SM407 rising edges before resetting to zero. This straightforward method ensures seamless operation and accuracy in data tracking.
When it comes to PLC programming, time is of the essence and the scan cycle acts as the clock. If you find yourself stuck, consider reversing the M51 section to the top, M50 in the middle, and M49 at the bottom. Remember that timing is crucial in PLC programming, and knowing when an event occurs can be more critical than what actually happens. Any assistance in this matter would be greatly valued.
Another potential solution can be achieved by utilizing the SM407 pair, which is essentially the same as a single rising edge trigger for efficiency. The Latch and Unlatch (L and U) instructions in the PLC are analogous to Delta's Set and Reset (S and R) instructions. This strategy allows for the extension of the M49 pulse through the M50 and M51 pulses, as well as the extension of the M50 pulse through the M51 pulse. It is crucial to ensure that each MODRW only triggers on the rising edge of these bits for optimal performance. It is important to note that this method may not be effective if the order of latches/sets on the second rung is reversed. Remember, the timing of events is often more critical than the events themselves.
One of the easiest and most straightforward solutions to read more Modbus registers in the future is by utilizing a counter with a built-in edge detector and integer comparisons. This method is not only simple but also highly customizable and scalable. By adding just two new instructions and adjusting the counter preset, additional Modbus registers can be easily integrated. Additionally, the MODRW instructions can directly replace the coils writing M49/M50/M51, eliminating the need for those specific bits. This streamlined approach not only simplifies the process but also enhances efficiency.
Hey there, it sounds like you've been doing a remarkable job, especially considering your status as a beginner! PLCs can certainly be tricky. It seems like you're having issues with multiple readings. As this appears to be a synchronicity problem, it's crucial to make sure you're opening and closing contacts correctly. This could simply be a coding syntax issue - don't forget that even a misplaced comma or semicolon can cause major headaches. If possible, try to study the behavior of your program with small step-by-step debugging, exploring the state of your contacts just before and after each MODRW function call. It may also be a good idea to consult with Delta's technical resources or community, as the problem might be specific to the AS218RX model. Keep persevering, and remember that even experienced engineers run into similar issues. You're learning, which is the most important thing!
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Answer: Answer: The main challenge is obtaining the necessary values from the inverter as the devices operate differently, leading to difficulties in communication and data retrieval.
Answer: Answer: The individual successfully resolved the issue by implementing a pulse contact, which allowed the value to update with each pulse. However, they encountered difficulties in performing multiple readings afterwards.
Answer: Answer: The individual believed that opening and closing a contact for each MODRW function in the program was necessary, but faced challenges in executing this correctly due to limited experience in PLC programming and lacking basic fundamentals.
Answer: Answer: Seeking assistance and guidance from more experienced individuals in the field can be beneficial for troubleshooting code and resolving issues with communication and data retrieval in the PLC programming process.
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