I am currently brainstorming ideas for modifying a machine at my workplace, specifically a 1756-L73S Controller. The machine includes a main conveyor that runs at about one revolution every 10 minutes, with variable speeds throughout the day. There is also a pusher conveyor that pushes products onto the main conveyor every 30 seconds. Both conveyors are controlled by VSDs and are integrated into the original PLC code, functioning properly. My challenge is to sync the speed of the pusher conveyor with the varying speed of the main conveyor. My idea involves using a proximity sensor on an intermediate gearbox shaft to count pulses, aiming for around 50 pulses per shaft rotation (equivalent to about 600 pulses per 1000mm of belt travel). I plan to count pulses for 20 seconds, store the value in memory, and repeat the process for another 20 seconds to compare the two values and determine any deviation if the main conveyor speed changes. This simple concept does not require precision, and the deviation value can be used to adjust the pusher conveyor speed accordingly. As a novice in PLC programming, I appreciate a straightforward approach. Thank you for your help.
"Both conveyors are operating smoothly with the help of Variable Speed Drives (VSDs) that have been integrated into the PLC code. How are they currently being controlled? If the control involves an analog signal from the PLC to the VSDs for speed regulation, you can utilize the main conveyor's set speed to determine the optimal speed for the pusher conveyor." Calculate the pusher conveyor speed set point based on the main conveyor's commanded speed.
When working with belt conveyors, it is vital to place the sensor on the non-driven shaft. Consider using an encoder or creating a toothed wheel with proximity to detect pulses effectively. This setup will ensure accurate monitoring and control of the conveyor system.
Simplify your process by using the current speed of one conveyor as the target speed for the other. If there are gearboxes with different ratios involved, some basic calculations may be required. However, if there are no gearboxes, adjusting the speeds in the code should be a straightforward task that can be completed in just 5 minutes. With Variable Speed Drives (VSDs) in place, external forces are not necessary to determine the speeds as the information is readily available.
To determine the correct ratio of gearboxes for the main conveyor and other conveyors, first find the actual value of the main conveyor. Calculate the ratio between the main conveyor gearbox and the other conveyor gearbox. For example, if the main conveyor gearbox ratio is 200 and the other conveyor's I/P to O/P ratio is 100, you should create an analog output for the main conveyor's RPM by multiplying it by 100 and dividing by 200 for the same speed. Please note that this logic will only work if the drive motor's maximum RPM is the same for all conveyors.
If I had to make an educated guess, I would say that there is a popular amber beverage labeled with multiple X's passing through these conveyors. Before anything else, if the primary conveyor is equipped with a Variable Speed Drive (VSD) and its speed is being adjusted, you should be able to synchronize the pusher speed accordingly using the same method. What obstacles do you encounter in doing so - are they related to separate Programmable Logic Controllers (PLCs)? It would be advisable to explore this option before considering any others. If for some reason this approach is not feasible, using a proximity sensor to count pulses is a practical method, especially if precise accuracy is not critical. However, as Peter suggested, you may want to consider placing the sensor on a non-driven shaft to account for any belt slippage (though there is still a possibility of slippage on the non-driven shaft). Ultimately, the exact location of the sensor may not significantly impact accuracy if it is not a crucial requirement. There are a few alternatives to consider, depending on the frequency of pulses. If multiple pulses are detected per second, you could tally the pulses within a fixed timeframe, calculate the speed, and repeat the process. It may be beneficial to reduce the timeframe to 3-5 seconds based on pulse frequency. Additionally, ensure that the pulse rate does not necessitate a high-speed counter card. However, if the pulses are spaced a couple of seconds or more apart, a different approach should be taken. Measure the time between each pulse to calculate the instantaneous speed. Store the last 5-10 intervals in an array and utilize a moving average for a more stable figure. While this may seem complex for programming novices, there are numerous examples available in forums to guide you through the process. To reiterate, the initial step should be to utilize the main conveyor's speed reference directly, rather than devising a new method to calculate it using sensors and timers. And lastly, a warm welcome to the forum!
I think you have a solid plan here. The usage of a proximity sensor to count pulses is a practical approach. Recognizing that it doesn't require absolute precision is also wise, as variability is a common issue in industrial settings. One thing you might want to consider is the time window for counting pulses. You chose a 20-second window, which could be adequate, but depending on the variations in the conveyor speeds, you might find that a longer or shorter timeframe gives you a more accurate representation of the speed. But as each operation has its individual quirks, it's all about tailoring your approach to fit your specific needs. Good luck with your modifications!
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Answer: - One approach is to use a proximity sensor on an intermediate gearbox shaft to count pulses and compare them to determine any deviation in conveyor speed. This deviation value can then be used to adjust the speed of the pusher conveyor accordingly.
Answer: - The 1756-L73S Controller can be utilized to integrate the control of both the main conveyor and the pusher conveyor, allowing for synchronization based on the detected deviation in conveyor speeds.
Answer: - Counting pulses for 20 seconds allows for collecting sufficient data to compare the speed of the main conveyor over time, enabling the PLC program to make accurate adjustments to the pusher conveyor speed.
Answer: - By counting pulses on the intermediate gearbox shaft, the proximity sensor provides real-time feedback on the speed of the main conveyor, facilitating the adjustment of the pusher conveyor speed to maintain synchronization.
Answer: - The proposed method is straightforward and does not require high precision. By implementing a simple concept of counting pulses and comparing values, even
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