I have been struggling to find a solution to my issue, as I am using AB RSLogix500 with SLC 5/05 CPU for my control system. My setup includes a simple three-button control panel with options for Speed up, Slow down, and Emergency stop (Estop). I am seeking to develop a logical sequence that will regulate an analog output (ranging from 0-10V) based on the specific input received (Speed up, Slow down, or Estop). It is crucial to note that Speed up and Slow down functions have different adjustment rates compared to Estop, which requires an immediate stop. Thus far, I have been experimenting with using a RMP instruction to achieve this control logic. However, I am facing challenges in assigning different timing intervals between RMP instructions. Could anyone suggest a faster and more effective method to accomplish this task successfully?
Counters can be utilized by implementing a "CTU" and a "CTD" instruction using the same counter address (such as C5:0). This setup should include three distinct self-resetting timers: one for increasing speed, one for decreasing speed, and one for emergency stops (e-stops).
Can you clarify how the "Speed Up" button functions? Does holding it down gradually increase speed, or is speed incremented by pressing the button repeatedly? Additionally, the description of the E-Stop suggests it acts more as a stop button than a true emergency stop feature.
Norml inquired about the functionality of the "Speed Up" button, wondering if holding it down gradually increases the speed or if pushing it repeatedly does so in steps. Additionally, there was concern about the description of the E-Stop, which seemed more like a regular stop button rather than an emergency stop. To clarify, holding the button will smoothly adjust the speed (e.g. from 0-10V in 15 seconds), while the E-Stop will quickly decrease the output (e.g. from 10V to 0 in 7 seconds). Hopefully, this explanation clears up any confusion.
One effective strategy suggested by Mickey is to utilize counters by implementing both a "CTU" and a "CTD" instruction with the designated counter address (e.g. C5:0). Additionally, setting up three distinct self-resetting timers can help control the speed increase, decrease, and emergency stop functions. However, the challenge lies in adjusting the counter to effectively modify the 0-10v analog signal and determining the rate at which the signal should increase or decrease. This requires a thoughtful approach to ensure optimal signal adjustment and system performance.
Programming the Jnox system for a consistent rate of output increase or decrease is fairly simple. For instance, if the analog output card has a range of 0-32767 for a 0-10V output, you can smoothly ramp up the output from 0 to 10V over 15 seconds by incrementing by one-fifteenth of 32767 each second. To achieve a smoother transition, you can increase by 218 every 0.1 seconds, or even smoother, by 22 every 0.01 seconds. To control the rate of output adjustment, you can use buttons to input values into the programming for raising/lowering (e.g. 22) or Emergency Stop (e.g. 250). It is essential to include limit-checking on the values sent to the Analog Output to ensure they fall within the accepted range. It is important to note that the term "EStop" should be used carefully, as what is described in the system functionality may not be recognized as an Emergency Stop but rather a "Faster Stop." Emergency Stops should not be solely controlled by a PLC system for safety purposes.
You may want to explore using a combination of scaling (SCP) and output latch (OTL) / output unlatch (OTU) instructions in this setup. The SCP instruction can be utilized to adjust the analog output based on specific input, considering you have a known range of 0-10V. Combine it with the OTL/OTU instructions to respond to the Speed Up, Slow Down, and EStop buttons. For instance, if Speed Up is pressed, you can increment the SCP's output a certain rate, and conversely, decrease when Slow Down is pressed. EStop can trigger an OTU to halt the operation right away – ensuring immediate system stop. The effectiveness of this would rely heavily on the timeslice settings for your SLC 5/05 which can be adjusted in RSLogix500's processor status file.
It sounds like you're on the right track with the RMP instruction, but for better control over your speed adjustments, consider using a combination of the RMP function with separate timers for each button action. By creating distinct timers for the Speed up and Slow down buttons, you can manage their adjustment rates independently. Then, when Estop is pressed, you can set a high-priority condition that immediately halts the analog output. This way, you maintain smooth transitions while ensuring safety with the emergency stop. It might also help to implement a state machine to simplify the logic and visualize how different inputs interact with your output. Good luck!
It sounds like you're on the right track with using the RMP instruction, but if you're struggling with timing intervals, have you considered implementing a state machine for your control logic? This way, you could define different states for Speed Up, Slow Down, and Estop, along with the corresponding output value and timing for each state. By doing this, you could quickly switch between states while keeping your timing logic clear and manageable. Also, remember to debounce your buttons to avoid any erratic behavior during fast presses, especially for your Estop. This might help streamline your adjustments and ensure that all outputs respond as you expect!
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Answer: Answer: To achieve this, you can develop a logical sequence in RSLogix500 that regulates the analog output (0-10V) based on the specific input received (Speed up, Slow down, or Emergency stop). You may need to consider different adjustment rates for Speed up, Slow down, and Emergency stop functions.
Answer: Answer: Challenges may arise when trying to assign different timing intervals between RMP instructions for Speed up, Slow down, and Emergency stop functions. It is essential to find a method that allows for effective control logic without these timing issues.
Answer: Answer: While experimenting with RMP instruction, you may face challenges in assigning different timing intervals. Considering this, it would be beneficial to explore alternative methods or instructions within RSLogix500 that can provide a more efficient solution for controlling analog output with varying adjustment rates for Speed up, Slow down, and Emergency stop functions.
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