Hello everyone! I am seeking assistance with understanding the connection between my ABB VFD and Rockwell PLC. I have configured the VFD parameters following the provided ABB worksheet for ODVA extended parameters. An image of the parameter settings from the ABB Spreadsheet has been uploaded for reference. My main issue lies with the speed reference control. When sending a speed reference command from the PLC to the VFD over Ethernet, such as 100 RPM, I expect the reference value returned from the VFD to match exactly. However, this is not the case. Despite sending a reference of 100 RPM as an INT data type per the ABB documentation, I receive a value of 1111 RPM. While I understand this value may actually represent 111.1 RPM, consistent with other data transfers, the discrepancy of 11.1 RPM is causing a system tolerance issue. I am seeking insight from ABB and Rockwell experts on the origin of this additional 11.1 RPM and how I can calibrate or eliminate it to ensure consistent matching of sent and received references. Thank you in advance for any assistance provided!
Do you have an encoder integrated into your drive motor setup?
Unfortunately, this system does not have an encoder. It's important to note that the return reference does not represent the actual speed of the system; rather, it pertains to the VFD's control reference command. Essentially, it validates that the Commanded speed in the PLC aligns with the instructed speed in the VFD's control algorithm.
I have discovered the solution to my problem, and it turned out to be simpler than I had anticipated. The data returned is calibrated on a scale of 0-20000. Therefore, all I had to do was adjust the data to align with the 0-1800 RPM format that I needed.
After coming across a solution to my problem, I realized it was actually quite simple. The data I received was on a 0-20000 scale, whereas I needed it to be in a 0-1800 RPM format. When the drive is in "scaler" or "V/hz" mode, the reference and feedback are based on the motor's synchronous speed. However, when switched to vector mode, the reference and feedback units are in 1:1 rpm. For further clarification, you can refer to the FEIP-Manual.
It appears that you might be dealing with an issue related to scaling. In some systems, the PLC might default to using a scale factor for certain analog signals such as RPMs, which may explain your discrepancy of 11.1 RPM. You might need to adjust the scaling settings in your PLC to match the exact values that your VFD is outputting. I would suggest first checking the scaling setting in your PLC setup and matching it with your VFD. However, if you've already done this and it hasn't solved the problem, you might need to reach out to ABB or Rockwell's technical support for more detailed assistance.
It sounds like you're facing a frustrating issue with the scaling or data conversion between your PLC and VFD. One possibility is that the VFD expects the speed reference in a different format, perhaps floating-point rather than integer, which can sometimes lead to unintended scaling issues during transmission. Make sure to double-check both the data type and the scaling settings in both your Rockwell PLC and ABB VFD configurations. Also, verify if there's any parameter setting in the VFD that deals with scaling factors for RPM. Calibrating these could help align the values better. It might also be worth reviewing any documentation on data handling peculiarities between the two systems; sometimes they can behave unexpectedly with edge cases. Good luck!
It sounds like you’ve done some thorough troubleshooting! The issue with the discrepancy might actually stem from the way the VFD processes the speed reference, particularly relating to how it scales the values. Check to see if the VFD configuration has any scaling factors or units that might convert your INT command to a different format—sometimes they use floating-point numbers or divide by factors like 10 for proportional representation. Additionally, confirm that the data type matches between the PLC and the VFD; even minor mismatches can result in interpretation differences. Consider reviewing the parameter settings again in detail or testing with diverse reference values to see if the pattern holds true across the range, which could help pinpoint the problem. Good luck!
It sounds like you're dealing with a frustrating issue with scaling between your PLC and VFD. When you send the speed reference as an integer, it might be that there's a scaling factor or conversion that needs to be applied. Often, VFDs expect the speed in a certain format or units (like tenths or hundredths), and that could explain why you’re seeing that extra decimal. I’d recommend double-checking the VFD documentation for how it interprets incoming values and ensuring that your PLC is aligning with that expected input format. Also, look into any scaling parameters that might be configured in the VFD, as adjusting those could help eliminate the discrepancies. Good luck, and I hope you get it sorted out soon!
It sounds like you're encountering a scaling issue with the speed reference you're sending to the VFD. Often, VFDs can interpret the input value based on their internal scaling settings. I recommend checking the parameter on the VFD that defines the scaling factor for speed references—sometimes it might be set to a different unit scale (like tenths of RPM) which sounds like what's happening in your case. Additionally, verify that both your PLC and VFD are configured to use the same units for speed references. It might also help to review the communication settings in both devices to ensure there’s consistency. If adjustments to the scaling don’t solve the discrepancy, consider using a calibration routine in your PLC to compensate for the offset. Good luck!
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Answer: 1. Why is there a speed reference discrepancy between the ABB ACS580 VFD and AB ControlLogix PLC? - The discrepancy may be due to how the speed reference values are interpreted and transferred between the devices.
Answer: - You may need to calibrate or adjust the parameter settings in both the VFD and PLC to ensure accurate speed reference communication.
Answer: - The discrepancy could be related to data type conversion, scaling factors, or communication protocols between the ABB VFD and Rockwell PLC.
Answer: - You may need to review and adjust the data type settings, scaling factors, or communication parameters to address the discrepancy and achieve accurate speed reference control.
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