Siemens ESM - Manual (Page 56)

Interfaces, Displays and Operator Controls
Industrial Ethernet OSM/ESM
52 C79000-Z8976-C068-10
OSM/ESM in the Standby Mode:
• ITP XP Standard Cable 9/9 not plugged in, short-circuited or broken
• Bad standby configuration: The partner device connected via the ITP XP
Standard Cable 9/9 is switched to standby.
• If there is an incorrect link status on a standby port.