behnam ba

hi

i want Find out the remaining volume ob 35 without having to wincc in simatic manager

best regard

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Split from OB 35.

OB35 in PCS7: Simple Explanation

• What is OB35?
  OB35 is a program block in Siemens PCS7 that runs automatically at regular time intervals (e.g., every 100 ms). It's used for tasks that need to happen at precise times, like controlling processes or reading sensor data.

How OB35 Works

1. Cyclic Execution: OB35 runs repeatedly based on the time you set (e.g., every 100 ms or 1 second).
2. Higher Priority: OB35 can interrupt slower tasks (like the main program in OB1) to ensure critical tasks are not delayed.
3. Use Cases: Ideal for tasks that need regular updates, such as PID control or monitoring key values.

How Much Data Can OB35 Handle?

• Depends on CPU Power: Faster CPUs can handle more data.
• Cycle Time Matters: The shorter the time interval (e.g., 10 ms vs. 1 second), the less data or logic OB35 can handle.
• Avoid Overload: If OB35 tries to handle too much, the CPU can become overloaded, causing delays.

How to Check Limits

1. Monitor CPU Load: Use the Siemens engineering tool (STEP 7 or TIA Portal) to see if the CPU load stays below 80%. If it's too high, reduce OB35's tasks or increase its time interval.
2. Test Execution Time: Check how long OB35 takes to finish its work and compare it to the interval you've set.
3. Optimize Code: Simplify the tasks in OB35 to make it run faster.

Tips

• Keep It Simple: Only put critical tasks in OB35 to avoid overloading.
• Distribute Work: Move less important tasks to other program blocks.
• Use Tools: Siemens diagnostics can show how OB35 affects the CPU.