Siemens SIMATIC NET Operating Instructions Manual page 67

The slot time calculation takes into account only the optical network and the attachment of
nodes to the OLM in each case via a maximum 20 m long RS485 bus segment. Longer RS-
485 bus segments must be included by adding them to the Length
Note
If the slot time is configured with a value that is too low, this can lead to malfunctions and
error displays on the OLM. The system LED flashes red/green.
Optical link module
Operating Instructions, 01/2020, C79000-G8976-C270-06
Planning/configuring
7.2 Configuration
.
FOC
67