A MZ07 CFD robot exchanged PROFINET Safety data with the PLC while its standard I/O remained unavailable. The configured process image was 64 input bytes and 64 output bytes for standard I/O, plus 8 input bytes and 8 output bytes for safety. The confirmed cause was enabled I/O Simulated Mode.
Identify the communication split
Working safety communication confirms that the PLC can detect the robot through the safety connection, but it does not prove that standard process I/O is active. Treat safety data and normal I/O as separate diagnostic paths.
| Data area | Configured input | Configured output | Observed state |
|---|---|---|---|
| Standard I/O | 64 bytes | 64 bytes | Not updating |
| Safety I/O | 8 bytes | 8 bytes | Visible to the PLC |
Correct the robot I/O mode
Channel 1 was configured for PROFINET Safety, but I/O Simulated Mode was also enabled. That mode was the confirmed reason normal I/O did not operate as expected.
- Open the robot controller's I/O configuration.
- Locate I/O Simulated Mode and disable it.
- Apply the configuration using the controller's normal procedure.
- Monitor the standard I/O data and confirm that inputs from the PLC are now visible.
Do not rely on the PLC-through selection
Selecting the Input/Output PLC-through option did not restore communication in this case. If safety data works but standard data does not, check I/O Simulated Mode before changing the configured byte counts or treating the safety connection as failed.
Verify the correction
Confirm that standard input data from the PLC changes at the robot after simulation is disabled. Retain the documented configuration of 64 standard input/output bytes and 8 safety input/output bytes unless the PLC and robot projects intentionally use different process-image sizes. If data still does not update, record any controller error and fieldbus LED status, then verify that the interface is configured for the required subordinate-device role according to the applicable manual.
FAQ
Why does PROFINET Safety work while the robot's normal I/O does not?
Safety communication and standard process I/O are separate data paths. In this case, enabled I/O Simulated Mode prevented the expected normal I/O operation even though the PLC could see the safety connection.
How do I restore standard PLC inputs on an MZ07 CFD robot?
Disable I/O Simulated Mode in the robot controller's I/O configuration, apply the change, and monitor the standard input data. The reported system could see inputs from the PLC after this mode was disabled.
What PROFINET I/O sizes were configured in this case?
The configuration used 64 input bytes and 64 output bytes for standard I/O, with 8 input bytes and 8 output bytes for safety I/O.