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To determine the difference between the configured and the real topology use the Diagnosis and do a "Online Comparison". This will also show, if all the device descriptions used match the real hardware, according to the parameters: Vendor ID, product code and Revision.
If you get one of the following Errors: 0xC0D5001D or 0xC0D5001E it means either the Output or the Input Configuration does not match.
To check, what is internally configured in the EPROM of the slave versus what´s configured via SyCon for the master, right click on the troublesome slave → "Connect" → "Configuration" → "Online Parameterize"
In the then opened window click "Start Upload" and wait until it finished. This may take a minute or longer.
You can now compare the Online and Offline Data to spot the difference in Process Data f.e.:
Slave
As for the Master the Slave Stack will also show it´s current state via the LEDs:
Most Errors have to be determined via the master.