Siemens SIMATIC NET PROFIBUS manual LED Indicators and Troubleshooting

5 LED Indicators and Troubleshooting 5.1 LED Indicators

5LED Indicators and Troubleshooting

5.1LED Indicators

PROFIBUS OLM

LED indicators System

CH 2 CH 1 CH 2 CH 3

CH 3

Receive

Signal

Intensity

GND

Fig. 14: LED indicators on the front plate

LED Indicator		Possible causes
System	 lights green	– The transmission rate has been recognized and the power supply is in order
	 not lit	– Power supply has failed (total failure*)
		– Power supply connected incorrectly
		– Module defective
	 flashes red	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.
	 flashes red/green	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

Signaling contact

no signal signal

no signal

no signal

* failure of both power supply sources with redundant infeed

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