The proven Ethernet technology makes Ethernet-based industrial networks very robust against interferences. Nevertheless, unexpected trouble may also occur here, so that in case of an emergency a quick troubleshooting option must be available. In contrast to the classic fieldbus, a diagnosis device cannot simply be engaged at any point of the bus in the daisy-chained Ethernet networks, since not all telegrams can be captured at every point of the network. Usually, a network is tapped directly behind the controller. Due to the point-to-point cabling used, integrating an analysis device in an Ethernet cabling requires splitting the Ethernet connection which, in turn, causes an abortion of the communication and a standstill of the system.

To prevent the Ethernet connection from being split, the netMIRROR Test-Access-Point (TAP) allows a continuous mirroring of the Ethernet traffic without influencing the network. Usually, a permanent TAP is installed directly at the controller to allow the disruption-free connection of a diagnosis device during operation. In addition, due to their passive construction, TAPs provide protection against possible, unintended interferences caused by a connected diagnosis device or a PC for telegram recording.