Enhance the efficiency of PLC operations and reduce execution time when performing similar tasks.
Note: Beginners don't need to focus on the practices mentioned here. They should read the program and understand the specifications to meet functional requirements.
1. When possible, use "words" instead of "double words," and prefer integers over real numbers for better performance.
2. Prioritize using IB, IW, ID, QB, QW, QD (excluding hardware connections), followed by M and S registers.
3. Avoid data type conversions if possible. If required, store intermediate variables in AC to minimize conversion steps. Plan memory usage early—like reserving VW0 when using VW2, so you can access it directly as VD0.
4. Reduce unnecessary network scans by grouping conditionally executed networks (especially AIW, AQW) into subroutines for timed or conditional calls.
5. Use the XOR instruction for bit reversal; this is a bit complex and requires careful debugging. It's recommended to work with binary numbers during programming.
6. Minimize the frequency of interrupts, provided process requirements are met.
7. Keep subroutines simple by reducing conditional checks and standardizing input/output parameters to avoid code duplication.
8. For repetitive or time-consuming tasks, implement sub-cycle processing. This includes spreading out initialization tasks across multiple cycles and slightly adjusting PID loop sampling times to prevent overlapping interrupts, ensuring a more stable scan cycle.
9. For subroutines with minimal input data, check if the input has changed before calling the subroutine. If not, skip it to reduce scan time.
10. Place bit variables in V511.7 and high-frequency VB/VW/VD variables in V4095 to optimize the scanning cycle.
11. Connecting SM0.0 in series with other signals only increases program size and execution time without any additional benefit. Avoid it unless necessary.
12. When sharing signals isn't needed, placing multiple instructions in the same network may add unnecessary operations. Consider converting to STL for analysis. Avoid horizontal inline logic to reduce the number of "AND" instructions.
13. Use immediate I/O commands sparingly to reduce PLC processing overhead.
14. Prefer using calculation result memory over transition memory to improve performance.
By following these optimization techniques, you can significantly enhance your PLC program's efficiency and reliability. These tips are especially useful for advanced users aiming to refine their code and achieve faster execution. Always test thoroughly after making changes to ensure stability and correctness.
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