Currently, I am in the process of developing my first program which involves incorporating 4 cascading timers to control the on and off cycles of Y001 and Y002. These cycles repeat for a certain number of XX cycles before resetting. Additionally, there is a non-resettable counter in place to monitor the total count. Within each cycle sequence, Y003 remains constantly active, while an analog output voltage from DA1V is set using DF3 in a math instruction. The variation of the output voltage is easily adjusted through a C-more micro HMI. However, my main concern lies in ensuring that the analog output is only active when a counter sequence is running, similar to the behavior of Y003. Currently, the analog output remains on continuously as long as the PLC is powered up. I believe implementing a copy instruction may solve this issue, but I am uncertain about how to structure it properly. For a visual reference, please refer to the attached image of the current rungs.
To ensure that the analog output is at 0 VDC when Y3 is switched off, consider adding a branch to your ladder logic that sets a constant value and conditions it accordingly. You have the option to utilize either the CPD or Math instructions for this task. I suggest converting the constant to a retentive float, allowing for easy runtime value adjustments. In fact, it would be beneficial to apply this approach to both values. In some cases, an output of 0.1 VDC may be more suitable than zero in practical applications. Instead of manually editing the logic during runtime, consider adjusting the "off" value in a dataview or HMI interface for convenience and efficiency.
In a recent update, @OkiePC brought up a valuable point regarding the implementation of a NC Contact reading the value of Y003 on the first rung. This adjustment not only fixes a typo but also improves readability and understanding of the program logic.
I realized it is too late to make changes, but instead of CPD (Copy Data), please use the term Copy instruction. When selecting options, choose Copy Single and specify a source address.
Thank you, drbitboy, for your suggestion. I tested it (with and without Y003 NC contact), but now I am not getting any analog output voltage in any state. OkiePC, I am not entirely clear on your proposal. I did consider if a copy command might be necessary. The image attached shows how I managed to display a counter output on the HMI, so I am thinking a similar approach may work. To provide context, envision a blindfolded individual with arms outstretched in a dim tunnel, attempting to navigate their way out - that's me when trying to program!
NewGuy2024 inquired about OkiePC's proposal, suggesting it may involve using a copy command to manipulate analog output. This process relies on DF3 writing to the correct channel of the analog card to regulate the brake, assuming the scaling meets the requirements. The Data View feature enables users to modify values in a PLC address without the need to adjust the logic. However, this function is only applicable to values not being overwritten by other PLC operations. In the screenshot provided, no current values are displayed as it is not connected to a PLC online.
Based on your description, it does sound like a copy instruction could help solve your issue. However, remember a copy instruction transfers a value from a source to a destination, so you'll need to ensure the condition for activating the analog output is tethered to the conditions for running the counter sequence. Alternatively, you could consider adding an intermediary, such as a logical AND gate, where one input is the counter sequence activation and the other is the PLC power status. This could ensure that the analog output is only active when the counter sequence is running, mirroring the behavior of Y003. In terms of structuring, you could, for example, denote '1' as the active state for the counter sequence, and use the AND gate to control the analog output. If the counter sequence isn't active ('0'), the output would be '0' no matter the status of the PLC power. But, always remember to verify the instruction's compatibility with your specific PLC model. Of course, this is all hypothetical and depends on the rest of your code architecture, but hopefully this gives you a starting point!
Sure, I can see where you're coming from. Controlling the analog output can be a bit tricky, but a couple of things might help. You could consider using a contact in series with the analog output that correlates to your counter sequence. Essentially, this contact would close when your counter sequence is active, and open when it's not, thereby controlling the flow to your analog output. For a copy instruction, you basically want to map the conditions of your counter sequence to your output - not complex structurally, but you should tread carefully when it comes to resource allocation and response times. Hope this helps!
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Answer: - To control the activation of an analog output based on PLC cycle sequences, you can use a copy instruction to ensure that the analog output is only active when a counter sequence is running. Make sure to structure the copy instruction properly within your program.
Answer: - Cascading timers are used to create time delays and control the on and off cycles of outputs Y001 and Y002 in a sequential manner. This helps in managing the timing and repetition of certain processes within the PLC program.
Answer: - You can easily adjust the analog output voltage using a C-more micro HMI by setting up the necessary communication protocols and interface between the HMI and the PLC. This allows you to interact with the analog output parameters and make adjustments as needed.
Answer: - The non-resettable counter serves the purpose of monitoring the total count of cycles or events within the program. It provides valuable feedback on the accumulated count without being reset, allowing for better tracking and analysis of the system's operation.
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