A TIA Portal program behaves as expected in PLCSIM, but some positive-edge contacts flicker after connecting Factory I/O. The evidence points to an I/O address-mapping mismatch as the first condition to test. The available information does not establish a TIA Portal defect, a scan-time fault, or a problem with the edge-detection instruction itself.
Identify the Mapping Boundary
Separate the simulated logic result from the external I/O result. Because the program runs correctly in PLCSIM and the symptom appears with Factory I/O, first compare Factory I/O offsets with the addresses assigned to PLC tags. An incorrect offset can make the program monitor a different input bit than the intended Factory I/O signal.
Apply the Proposed Address Map
| Data direction | Factory I/O offset | TIA Portal starting address |
|---|---|---|
| Inputs | 10 | I10.0 |
| Outputs | 0 | Q0.0 |
Use this map consistently across the Factory I/O driver configuration and the TIA Portal tag table. The offsets and starting addresses form one test configuration; changing only one side will not validate the proposed correction.
Correct and Verify the Configuration
- Set the Factory I/O input offset to 10.
- Set the Factory I/O output offset to 0.
- Assign PLC input tags from I10.0 and output tags from Q0.0 in TIA Portal.
- Reconnect Factory I/O and monitor the affected input tag and its positive-edge contact.
- Operate the corresponding Factory I/O input once and confirm that the PLC tag changes only with that intended signal. If flickering persists, record the configured tag address and the observed input state; the supplied evidence does not identify a further root cause.
Interpret the Test Result
If the flickering stops after both sides use the stated map, the result supports an address-offset mismatch as the cause. If the raw input tag itself continues to alternate, the edge contact is reacting to a changing source signal; this test alone does not determine why that source changes. If the raw tag remains stable while the edge result appears incorrect, additional program and configuration evidence is required before attributing the behavior to the edge logic.
FAQ
Why do positive-edge contacts flicker only with Factory I/O?
The program works in PLCSIM, so test the Factory I/O-to-PLC address mapping first. A mismatched offset can connect the logic to an unintended input bit.
What Factory I/O offsets should I test with TIA Portal?
Set the input offset to 10 and the output offset to 0, then map TIA Portal inputs from I10.0 and outputs from Q0.0.
How do I verify that the Factory I/O address correction worked?
Monitor the raw PLC input tag and the positive-edge contact while operating the corresponding Factory I/O input once. Confirm that the intended tag changes with that signal and that the unexplained flickering stops.