BECKHOFF EP1908 - Manual (Page 18)

Operation
16 EP1908-0002
4.1.5.3 EtherCAT- Fieldbus LEDs
LED displays
LED Display Meaning
IN L/A off no connection to the preceding EtherCAT module
lit LINK: connection to the preceding EtherCAT module
flashing ACT: communication with the preceding EtherCAT module
OUT
L/A off no connection to the following EtherCAT module
lit LINK: connection to the following EtherCAT module
flashing ACT: Communication with the following EtherCAT module
Run - see section 4.4.1
4.1.5.4 EtherCAT cables
For connecting EtherCAT devices only Ethernet cables that meet the requirements of at least category 5
(CAT5) according to EN 50173 or ISO/IEC 11801 should be used.
Note
Wiring recommendations
Detailed recommendations for EtherCAT wiring can be found in the documentation
"Design recommendations for EtherCAT/Ethernet infrastructure", which is available for
download from
www.Beckhoff.com .
EtherCAT uses four cable wires for signal transmission. Due to automatic cable detection (auto-crossing)
symmetric (1:1) or cross-over cables can be used between EtherCAT devices from BECKHOFF.