The Beckhoff master (e. g. EL6731 master terminal) does not cyclically request the status of slaves.

This is why in this case no external (not activated on the device itself) Phantom slaves (see chapter Diagnostics in the I/O Manager) can be detected in the diagnosis.

Measurement of the bus voltages (see chapter Display of bus voltages in the I/O Manager) is also not possible due to the missing status telegrams.