The invention relates to an IO-Link system comprising at least one IO-Link master (1), at least one IO-Link device (2) and at least one IO-Link-capable infrastructure component (30). The at least one IO-Link master (1) and the at least one IO-Link device (2) are connected via the at least one infrastructure component (30) and exchange data via a data channel (K1). The infrastructure component (30) has an apparatus (61, 62) for recording diagnostic data. A diagnostic channel (K2) is provided in the IO-Link system, via which diagnostic channel (K2) the diagnostic data can be sent and received between the at least one infrastructure component (30) and the at least one IO-Link master (1) separately from the data channel (K1).