Siemens SIMATIC NET PG PROFIBUS Operating Instructions Manual page 11

CH1, CH2 , CH3 (channel 1 to 3, yellow)
not lit:
lit yellow:
Image 3-1
PROFIBUS Optical Bus Terminal (OBT)
Operating Instructions, 04/2016, C79000-G8976-C122-07
Data is not being received
Data is being received
LEDs on the front panel
Functional description
3.4 Displays
11