Beckhoff FC1028 Manual page 18

TwinCAT configuration
The state of the individual EtherCAT slaves can be found in the State column. If, for example, the cable
connection between the two EK1100 EtherCAT couplers is interrupted, their state changes. The
message "LINK_MIS C" and "LINK_MIS A" then appears in the State column.
Although the connection between the EtherCAT couplers is interrupted, the EtherCAT Terminals
connected to the EK1100 EtherCAT couplers do not have a fault.
If the cable connection is interrupted at the same point without cable redundancy, a fault is displayed for
the terminals in the State column.
18 Version: 1.0 FC1028