Greetings PLCS.Net Forum! This is my first time posting, and I consider myself a novice in this field. I am encountering a crucial issue where my servo/linear piston is not correctly zeroed, causing a discrepancy between the actual physical position (47 mm) and the perceived position in Studio 5000 V35 (32 mm). This discrepancy poses a significant risk of mechanical damage. The equipment involved includes an A2198-C1004-ERS KINETIX 5300 servo driving an MPAIA3076RM14AMP series heavy-duty electric cylinder with a total range of 76 mm. The feedback and power/brake cables are new (2090-CPBM7DF-16AA033 m Power/Brake & 2090-CFBM7DF-CEAA033 m Feedback), and other hardware includes a 5069-L306ERM CompactLogix and a 2711P-T7C22D8S PanelView Plus 7. The piston controls the spacing of grind wheels, with soft limits set at 32mm and 58mm, and a home position at 34 mm. The HMI provides specific recipes for selected positions that the servo should reach and hold with a brake until a different recipe is chosen. While initial programming tests were successful manually, I am now facing difficulties automating functions like moving to the home position or selected recipe locations. I have attempted to rezero the drive/piston but have encountered limitations within the controller tags. I am seeking advice on how to restore/rezero my drive/piston alignment and prevent such issues in the future. Is there a way to avoid errors caused by code or power cycles? Am I misunderstanding absolute encoding and its ability to track position accurately? Additionally, I am considering adding limit switches for extra protection and would appreciate recommendations on sensor types and homing sequence tips. My goal is to achieve precision within 0.1 mm tolerance without introducing errors from sensor resolution. Thank you in advance for any guidance or insights you can provide. Warm regards,OhNo!
Explore the MAH instruction for Motion Axis Home. You have the option to home to a hard stop (consider limiting torque during this process) or home to a limit switch. The instruction also enables you to apply an offset. Additionally, you can utilize an SSV to reconfigure zero, although it may require some time to familiarize yourself with the process. Based on my own findings, homing to a hard stop at a low velocity with restricted torque has yielded optimal outcomes. It is highly recommended to refer to Rockwell's comprehensive documentation on servo programming for further guidance and clarity on any queries you may have. Downloading and thoroughly reading the documentation will provide you with valuable insights.
When setting up your motion control system, it's important to follow the MAH (Motion Axis Home) instruction carefully. You have the option to home to a hard stop with limited torque or to a limit switch, and can also apply an offset if needed. Consider using an SSV to redefine 0 as well. From my experience, homing to a hard stop at low velocity yields the best results. It's recommended to refer to Rockwell's servo programming documentation for detailed guidance. By downloading and reading these manuals, you'll find answers to all your programming questions. Don't hesitate to explore specific programming manuals for further insights. Cheers! --OhNo!
For access to detailed information on motion control systems, you can explore the document titled "Motion Control User Manual" on the Rockwell Automation literature website. This resource provides valuable insights into optimizing motion control in industrial settings.
Do absolute encoders maintain their position for the full 4,096 turns inside the piston? Absolutely! At some point, a reference point needs to be established to define zero position on the axis in terms of encoder turns and counts. This relationship between motor turns and displacement in millimeters is a key aspect of the drivetrain mechanism in Studio 5000. One common method for establishing this zero point is using a physical switch that triggers when the mechanism reaches a "home" position. There are various approaches to handling this, such as stopping when the switch is activated and defining that as zero, or moving in reverse at a slow speed until the switch is released and then setting that as zero. Some mechanisms allow for a "home to hard stop" function, where the motor's torque is reduced and the mechanism is moved until it hits an end stop and detects an increase in current without a change in position. ControlLogix does not have a built-in home-to-hard-stop function, but some A-B branded indexing drives offer this feature. Setting the "home" or "zero" position of the axis is typically accomplished using the Motion Axis Home (MAH) instruction. This can be done through the Axis Properties menu by selecting the Homing window, setting the Sequence to Immediate, and clicking Apply. Alternatively, the MAH instruction can be executed in the user program with the arguments configured in the Axis settings. It's important to differentiate between Active + Immediate and Passive homing methods. Active + Immediate immediately sets the axis position to the specified value on the Homing screen, while Passive homing relies on a Z-pulse signal once per revolution for accuracy, often used for feedback-only axes that move freely.
When setting up your system, it is essential to consider how it operates daily and how alignment is achieved during assembly or maintenance. Without an encoder or motor, determining the position of the grind wheels can be a challenge. Do you rely on a probe, switch, scale, or a laser tracker to measure against fixed frame parts? The absence of sensors or verification poses a risk of unauthorized adjustments or incorrect resets, leading to malfunctions. One approach is to align the machine using your preferred method and input the position for the Active/Immediate Home feature with the MAH. For precise homing functions, using accurate sensors and going at a slow pace is recommended. A limit switch or proximity sensor with Passive Homing can also be utilized to set the zero point for the Axis. To ensure accuracy, comparing the system's actual position with what the Axis indicates and applying any discrepancies as an offset is advisable.
Hey OhNo! Welcome to the forum. Your case sounds quite interesting. Now, usually when there's a discrepancy, it could be due to a misinterpretation of encoder output by Studio 5000 or possibly other mechanical factors. Maybe check for a backlash in your motion drive system, as that can throw off the absolute position slightly. Also, regarding absolute encoding, yes it can track position accurately. However, keep in mind it depends on things functioning correctly and as expected throughout the entire system, including power supply stability, noise interference and consistent operating conditions. In relation to adding limit switches, it's a good idea as a fail-safe approach. For the type of precision level you're targeting, I would recommend going for either capacitive or Hall effect sensors - they're favourable due to their high resolution and decent immunity to environmental factors. Lastly, don’t forget to check parameters for soft and hard limits, that could also prevent correct zeroing. There are tons of subtleties that could misinform the system about its position. So, it sounds like you may have to dissect the issue more granularly, testing each component individually and ruling them out as the cause of the problem. Hope this helps and best of luck!
Hi OhNo, welcome to the forum! Your misalignment issue might stem from either the control code or mechanical setup. To understand it better, you could try adding a "Machine Position" variable in the Software to track the physical position after home-setting, and compare it with the "Device Position" to check for discrepancies. If this doesn't solve the issue, it could be about how you're zeroing the servo. You may not be actually setting the encoder feedback to zero at the home position. In coordination with the 'Home' command, ensure that you're using the 'Reset Position' method in the drive or check the encoder feedback directly. Moreover, adding limit switches may help in tandem with this. Also, your goal for 0.1mm precision suggests that your feedback device may not be of the required resolution; hence consider upgrading the encoder to a high-resolution version. This will be critical in achieving your desired tolerance with integrity. That said, your thought process seems fine; you just might need a deeper dive into settings and routines! Good luck!
Hi OhNo, first off, welcome to the forum! Your issue does sound like a challenge. For re-zeroing your servo/linear piston, you may want to consult the manuals for both the servo drive and the piston to determine the correct re-zeroing procedures. If these methods still don't work, it might be a problem with the controller or the controllers' software. Regarding absolute encoding, it tracks position within a complete 360-degree revolution of the servo independently from the controller it's attached to. Ensure your servo detector is correctly installed and working properly. As for limit switches, inductive proximity sensors work well for metallic objects and have high repetitive accuracy, which would suit your requirement for ±0.1 mm precision. For homing sequence, you could consider the double touch homing process, which uses a slower second approach to ensure accuracy. Lastly, always remember to perfect your scripts, this will help minimize error occurrence. Hope this helps and good luck with your project!
Hi OhNo! Welcome to the forum! It sounds like you're dealing with a pretty intricate setup, and I can understand how frustrating this must be. For your zeroing issue, it might help to double-check your encoder settings in Studio 5000 to ensure they match the actual hardware settings. Since you're working with absolute encoders, make sure they’re configured correctly to retain their position after power cycles. Adding limit switches is a great idea; I recommend using mechanical ones for reliability, or proximity sensors if you want a non-contact option. For the homing sequence, a simple approach would be to use a slow jog towards the limit until triggered, then set the position accordingly. Keeping everything calibrated will help maintain that 0.1 mm precision you're aiming for. Good luck, and hopefully, you’ll sort this out quickly!
Hi OhNo!, welcome to the forum! It sounds like you're dealing with quite a complex setup, but you're definitely not alone in this. For the zeroing issue you're encountering, I'd recommend double-checking your absolute encoder settings, as it plays a crucial role in the servo's position tracking. If the encoder isn't correctly set up, it can lead to the discrepancies you're seeing. As for the homing sequence, if you're looking to implement limit switches, I suggest using normally closed (NC) proximity sensors, as they tend to provide more reliability in preventing any over-travel conditions. Make sure to incorporate logic in your program that will establish safe positions before moving to the home position or recipe locations—this can prevent accidental movement errors after a power cycle. Lastly, don't hesitate to reach out to support for your specific hardware; they can often provide tailored guidance that might clear up any confusion. Good luck, and I hope you get everything sorted!
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Answer: - To resolve misalignment issues, you can try rezeroing the drive/piston and ensuring proper alignment. Seek advice on troubleshooting and preventing such issues in the future.
Answer: - To prevent errors from code or power cycles, consider understanding absolute encoding for accurate position tracking and implementing proper rezeroing procedures.
Answer: - When adding limit switches for extra protection, consider sensor types and homing sequence tips to achieve precision within a 0.1 mm tolerance without introducing errors from sensor resolution.
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