Siemens SIMATIC NET PROFIBUS Owner's Manual page 445

L+ 24V (green)
Unlit:
Flashes:
Lit green:
CH1, CH2 , CH3 (channel 1 to 3, yellow)
Unlit:
Lit yellow:
Figure 3-1 LED Displays on the Front Panel
PROFIBUS Optical Bus Terminal (OBT)
C79000-G8976-C122-02
No power supply or internal power supply is
defective or short-circuited
Power supply present; Transmission rate
not yet set
Transmission rate set, power supply
O.K.
No data being received
Data being received
L + 24V
CH1
CH2
CH3
CH2 CH3
Functional Description
3-3