Subject: Seeking Programming Guidance for Hydraulic Motor Control Hello everyone, I hope this message finds you well. As a mechanical engineer venturing into self-teaching programming for a home automation project, I'm reaching out for assistance. My experience with programming is limited, and I’m hopeful my question is straightforward—something I may just not have encountered yet. Here’s an overview of my current setup: I have two sensors and a solenoid valve that controls a hydraulic motor. When **Sensor 1** detects its flag, I activate the hydraulic motor until **Sensor 2** detects its flag. The challenge arises because **Sensor 1’s** flag is mechanically triggered based on ground speed. If I’m moving too slowly or come to a stop while the flag is still in front of the sensor, the PLC continues to detect the flag, causing the motor to rotate beyond the intended limits. What I need is a way to program the system so that **Sensor 1** must reset—meaning it should stop detecting the flag before it can see it again—before allowing the motor to rotate and position **Sensor 2’s** flag again. I attempted to address this issue using a drum sequencer, where **Sensor 1** counts as "1 unit" and **Sensor 2** counts as "1 cup." I incorporated a timer in step one to give the flag time to clear **Sensor 1**, but I’m not satisfied with the results, as it only functions adequately. I've explored various methods, including bypassing the drum sequencer entirely, but I’m struggling to find a solution that works effectively. If anyone has the expertise or time to guide me through this process, I would be incredibly grateful. Thank you in advance for your help! Best regards, Derek *P.S. I am using a Productivity 2000 PLC from Automation Direct for this project.*
Seeking Additional Information: Please share more details about your project. What specific tasks are you aiming to accomplish (physically)? Which types of sensors are currently in use? While a drum sequencer could be an option, it may be excessive for your application, and I have a hunch it might not be necessary. I suspect that incorporating a one-shot trigger for the sensor input could resolve your issue, but this is just a preliminary assumption. More information would be helpful to provide accurate advice. -Ghost
**Title: Optimizing Hydraulic Motor Control with Inductive Proximity Sensors** Hello, fellow enthusiasts! My current project involves an innovative approach to controlling a hydraulic motor using a simple flag system. The primary goal is to synchronize the movement of a flag attached to a wheel with a hydraulic motor equipped with its own flag on the output shaft. Ideally, I'd like the motor to index just one full revolution each time the flag passes in front of the sensor, allowing for precise start and stop actions. However, I’m facing a challenge: when the wheel stops with the flag in front of the sensor, the motor continues running. This seems to be because the PLC (programmable logic controller) continuously scans the sensor and detects the flag, assuming it needs to keep the motor moving. My main obstacle is effectively programming the system so that the sensor registers the flag only once. After the flag is detected, I want the system to wait until the flag moves out of the sensor's range and reappears before allowing another indexing operation. This project is primarily a learning exercise for me, utilizing various spare parts available. I’m using an Automation Direct inductive proximity sensor, specifically the **AE1-AN-4F model**, which features an 8 mm diameter, 50 mm body length, tubular design, NPN configuration, and a nominal sensing distance of 4 mm. It is unshielded with a normally open (N.O.) output and has a 3-pin M8 quick-disconnect, all housed in a durable nickel-plated brass casing. If anyone could offer guidance or resources on achieving the one-shot functionality I need for this hydraulic motor control system, it would be greatly appreciated. I look forward to your insights to help steer my project in the right direction! Thank you! Best, Niese
I haven't personally utilized any products from AutomationDirect, so other forum members might provide more insight. However, I would be surprised if the functionality of the one-shot in AutomationDirect is significantly different from the ControlLogix that I'm currently using. A one-shot instruction will output a true state every time its input changes from false to true, but it will only activate for a single scan and won't remain true until the input transitions again. I recommend placing a one-shot on each sensor's input, ensuring they only provide a pulse when they initially detect the flag on the wheel or motor. You can then utilize these outputs to either seal or break the seal of your motor's running coil. -Ghost
If you're looking for valuable reading material, I recommend checking out the links below. They provide essential information on topics related to Automation Direct PLCs, specifically focusing on the Do-More series. It's worth exploring the entire site, as it offers a wealth of knowledge that could aid in your understanding. For detailed instructions, you can refer to this link: [Productivity 1000 Series PLC - Contact and Coil Instructions](http://accautomation.ca/productivity-1000-series-plc-contact-and-coil-instructions/). Additionally, you can learn how to create a one-shot in your PLC at this page: [How to Make a One-Shot in the PLC](http://accautomation.ca/how-to-make-a-one-shot-in-the-plc/). I suggest experimenting with the attached example, although it presumes certain aspects of your setup, such as the use of a spring return valve. This could serve as a good starting point for your project.
Niese inquired, "Could you provide further clarification on the concept of 'one-shot'?" Click to expand... My familiarity with Automation Direct products is limited. However, here's some general information: "One Shot" is a term used by Rockwell, but it is also widely referred to as "edge triggers" or "edge detection" across various brands. This instruction functions by comparing the current value of a variable to its value from the previous scan. The instruction will return true for a single scan only when the current value is true and the prior value was false. It's common to encounter several variations of this instruction, as it often compares one tag against the ladder status and differentiates between rising edge and falling edge scenarios.
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Answer: Derek is trying to control a hydraulic motor using two sensors and a solenoid valve. The main challenge arises when Sensor 1 detects its flag based on ground speed. If the system moves too slowly or stops while the flag is still in front of Sensor 1, the PLC continues to detect the flag, causing the motor to rotate beyond the intended limits. Derek needs a way to ensure Sensor 1 resets before it can detect the flag again to prevent this issue.
Answer: Derek attempted to use a drum sequencer approach where Sensor 1 is counted as "1 unit" and Sensor 2 as "1 cup." He included a timer in step one to allow the flag time to clear Sensor 1. However, he is not satisfied with the results because it only works adequately and does not fully address the issue.
Answer: Derek is using a Productivity 2000 PLC from Automation Direct for his project. This is relevant because the specific capabilities and programming environment of the Productivity 2000 PLC will influence the programming solutions available to him, such as the use of ladder logic, timers
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