Siemens SIMATIC NET Operating Instructions Manual page 29

Fibers used
PCF fiber
If you use PCF fibers, set the transmit power "Default" (S5 or S6 in position 1).
If you use PCF fibers S 200/230, neither a minimum cable length nor an attenuator is
necessary.
Plastic fiber S 980/1000
If you operate OLM / P11 V4, OLM / P12 V4 or OLM / P22 V4 along with the devices OBT,
IM151-1 FO, CP 5613 FO/CP 5614 FO, IM 467 FO, CP 342-5 FO or IM 153-2 FO and use
plastic fibers S 980/1000, note the following:
1. To connect the devices, use optical fibers with a minimum length of 30 m, refer to the
following graphic.
Figure 4-1 Minimum cable length when using plastic fiber S 980/1000 without fixed attenuators
As an alternative, you can use a fixed attenuator with an attenuation value between 5 dB and
15 dB.
1. Insert the fixed attenuator in the receive cable of the OLM.
2. Set the corresponding transmit level switch (S5 or S6) to "reduced".
Optical link module
Operating Instructions, 01/2020, C79000-G8976-C270-06
Operator control (hardware)
4.3 Reducing optical transmit power
29