3. Ethernet TAP

To capture the EtherCAT® traffic, EC-Monitor supports a variety of different Ethernet Test Access Points (TAP). These can be special real-time optimized TAPs with minimal propagation delay and extended diagnostic options, or simple 100MBit/s Ethernet switches. The only requirement is that the input (RX) and output (TX) traffic is forwarded to the EC-Monitor via a common up-link port.

The Ethernet TAP device can be inserted in the network between the EtherCAT® master and slaves or, if this is not possible, between two slaves. The position of the Ethernet TAP is detected automatically and the EtherCAT® traffic is processed accordingly.

The various Ethernet TAP devices can be automatically detected by the EC-Monitor via EC_T_MONITOR_INIT_PARMS::eEthTapType set to EC_T_ETHERNET_TAP_TYPE::eEthTap_AutoDetect.

3.1. Generic 100MBit/s Ethernet Switch

A generic 100MBit/s Ethernet switch with at least 3 ports can be used with EC-Monitor. The propagation delay can be up to 150 μs per port and should therefore only be used for slower cycle times.

To manually select this device set EC_T_MONITOR_INIT_PARMS::eEthTapType to EC_T_ETHERNET_TAP_TYPE::eEthTap_Generic.

3.2. Beckhoff ET2000

The Beckhoff ET2000 comes with propagation delay below 1 μs, a high-precision timestamp and extended frame error detection capabilities. The TAP offers the possibility to determine on which port the frame was received. The EC-Monitor uses this to evaluate whether it is a TX or RX frame. Therefore, the outgoing connection from the EtherCAT master should be connected to either port X1.0, X2.0, X3.0 or X4.0.

To manually select this device set EC_T_MONITOR_INIT_PARMS::eEthTapType to EC_T_ETHERNET_TAP_TYPE::eEthTap_Beckhoff_ET2000.

3.3. Dualcomm ETAP-1000

The Dualcomm ETAP-1000 has a propagation delay below 1 μs. Since it has no other extended capabilities it can be used as generic Ethernet TAP EC_T_ETHERNET_TAP_TYPE::eEthTap_Generic.

3.4. Hilscher netAnalyser

The Hilscher netAnalyser comes with propagation delay below 1 μs and it will be detected as generic Ethernet TAP EC_T_ETHERNET_TAP_TYPE::eEthTap_Generic.

3.5. Kunbus TAP Curious

The Kunbus TAP Curious comes with propagation delay below 1 μs, a high-precision timestamp and extended frame error detection capabilities. The TAP offers the possibility to determine on which port the frame was received. The EC-Monitor uses this to evaluate whether it is a TX or RX frame. Therefore, the outgoing connection from the EtherCAT master should be connected to either port A or C.

To manually select this device set EC_T_MONITOR_INIT_PARMS::eEthTapType to EC_T_ETHERNET_TAP_TYPE::eEthTap_Kunbus_TapCurious.

3.6. ProfiTap ProfiShark

The ProfiTap ProfiShark devices are USB3.0 based Ethernet TAPs with a propagation delay below 1 μs. Since the devices appear as a virtual Ethernet interface in the operating system they can be used as a generic Ethernet TAP EC_T_ETHERNET_TAP_TYPE::eEthTap_Generic.

3.7. Port Mirror

A TAP or switch with port mirroring functionality can also be used with EC-Monitor. Typically, a port mirroring device has four Ethernet ports, two input ports for the network and two mirroring output ports. Incoming traffic on the respective network port is mirrored to the corresponding mirror port.

In the EtherCAT® use case, this means that the Ethernet frames outgoing from the EtherCAT® master are mirrored on one port and the Ethernet frames returning from the EtherCAT® slaves are output on another port. Since EC-Monitor currently only supports one port for connecting to the TAP, the mirror port with the returning Ethernet frames must be connected.

This device must be selected manually by setting EC_T_MONITOR_INIT_PARMS::eEthTapType to EC_T_ETHERNET_TAP_TYPE::eEthTap_PortMirror.

Warning

Since only the returning frames are processed, inconsistencies occur in the process data image of the outputs for EtherCAT® frames with LRW commands.