Siemens SIMATIC NET PROFIBUS, Owner'S Manual, Page: 421 / 490

5.1 LED Indicators
25
5 LED Indicators and Troubleshooting
Version 1.0 8/00
5 LED Indicators and Troubleshooting
Fig. 14: LED indicators on the front plate
CH 1
System
PROFIBUS OLM
CH 2
CH 3
GND
Receive
Signal
Intensity
CH 2 CH 3
LED indicators
Possible causes
– The transmission rate has been recognized and the power supply is in order
– Power supply has failed (total failure*)
– Power supply connected incorrectly
– Module defective
Transmission rate has not yet been recognized
– No transmitting bus subscriber present
– No connection to a partner module sending frames
– Send and receive optical fibers have been transposed
– Transmission rate does not correspond to the PROFIBUS standard
– Only one active bus subscriber is connected, which is only sending tokens to
itself. The indicator must switch over after a second bus subscriber has been
activated (token frames on their own are not enough to set the transfer rate).
– The connected RS 485 segment is only terminated at one end.
Transmission rate recognized but
– the network slot time could not be determined (network parameter HSA is set
too low, no transmitting bus subscriber present)
– one optical port is set to ”Redundant optical ring“ mode, but not the second
(this operating mode must always be set at both optical ports)
– the slot time of the network configuration is too short
* failure of both power supply sources with redundant infeed
LED Indicator
System lights green
not lit
flashes red
flashes red /green
Signaling contact
no signal
signal
no signal
no signal
5.1 LED Indicators