Hello, I'm facing an issue while attempting to program in Ladder logic. I need two possible contacts to trigger an output. In the screenshot below, if BOT_EST_ALIM is true, all three outputs should be activated. However, MOT_EST_BALAN and MOT_EST_MIST should only be activated when their specific contacts are true. Currently, only the last two outputs are functioning correctly. MOT_EST_BALAN and MOT_EST_MIST in network #1 work as expected only when the last two networks are removed.
In Programmable Logic Controllers (PLCs), it is essential to only designate an output once to avoid conflicting conditions on different rungs. Ensure that the logic is combined effectively to use each output only once, preventing lower rungs from overriding upper ones. This practice optimizes PLC programming and ensures smooth operation.
It is unclear what you are using in this setup, but in general, the first rung activates all the coils that will be utilized in the following rungs. The software may vary in its functionality, but typically, each coil is restricted to a particular rung for proper operation.
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Learn from SCADA Joe's example. The coil instruction in PLC programming always outputs either a 1 or a 0 when its rung is evaluated during the scan cycle. Timing is crucial in PLC programming, as the scan cycle acts as the heartbeat of the system. The timing of events is often more critical than the events themselves. For a deeper understanding of the PLC scan cycle, be sure to check out this informative video series.
Mel pointed out that only the final two rungs are functioning correctly. None of the rungs are malfunctioning - they are simply not meeting your expectations because you may have a misconception of how PLCs operate. Click here to learn more about PLC functioning.
Based on your description, it sounds like you need to implement parallel checks in your logic, where BOT_EST_ALIM serves as a sort of 'master switch' for all three outputs, while MOT_EST_BALAN and MOT_EST_MIST operate individually when their specific contacts are true. For this, consider using an OR operator. If you implement your logic in a way that BOT_EST_ALIM OR MOT_EST_BALAN trigger MOT_EST_BALAN, and similarly for MOT_EST_MIST, that might solve the problem. Remember, in Ladder logic, an OR operation is symbolized by parallel/branch circuitry. Hope this helps, and do let us know of your progress!
Hi there! It seems like you have an interlocking issue that's causing the problem. Ladder logic relies on scanning from left to right and top to bottom, so your issue might be stemming from the arrangement of your networks. Start with BOT_EST_ALIM to capture the condition of all three outputs. Then, instead of removing the last two networks for MOT_EST_BALAN and MOT_EST_MIST, try placing them after the first network. Ensure that each has its own separate line going to the output, allowing them to operate independently based on their specific contacts. I hope this nudges you in the right direction!
It sounds like you might be running into a scoping issue with how your networks are interacting. In Ladder logic, it's crucial to ensure that the conditions for triggering outputs don’t conflict with each other across different networks. Have you checked if the conditions for MOT_EST_BALAN and MOT_EST_MIST might be getting inadvertently overridden by the logic in network #1? It might help to simplify your logic temporarily or isolate each network to see where the conflict arises, ensuring that the activation conditions for each output are independently evaluated based on their respective contacts.
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Answer: Answer: The issue may be related to the interaction between the specific contacts for MOT_EST_BALAN and MOT_EST_MIST in network 1 and the configuration of the other networks. Removing the last two networks may have an impact on the correct functioning of these outputs.
Answer: Answer: To activate all three outputs when BOT_EST_ALIM is true, the ladder logic programming should be structured in a way that ensures the appropriate contacts are connected to trigger the outputs in the desired manner.
Answer: Answer: The issue might be related to the sequence or arrangement of the networks in the ladder logic program. Adjusting the connections and conditions in the ladder logic program can help resolve this issue and ensure the correct activation of the outputs.
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