Siemens SIMATIC NET PROFIBUS - Manual (Page 445)

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