Installation and Maintenance
5.7 LED Displays and Troubleshooting
SIMATIC NET PROFIBUS, Optical Link Module
38
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5
LED display
Possible causes
Signaling
contact
lit green
- The transmission rate was detected and the voltage supply is ok
does not signal
not lit
- Voltage supply outage (complete outage, with a redundant supply, outage
down of both supply voltages)
- Voltage supply connected wrongly
- Module defective
signals
flashes red
Transmission rate not yet detected
- There is no transmitting bus node
- No connection to a partner module sending frames
- Transmit and receive fiber-optic cables are swapped over
- Transmission rate does not correspond to the PROFIBUS standard
- Only one single bus node is connected, which only sends token to itself. After
activation of a second bus node, the display must change (token frames are
not enough to set the transmission rate)
- The connected RS-485 segment is only terminated at one side
does not signal
System
flashes
red/green
Transmission rate detected but
- The slot time of the network could not be detected yet (network parameter
HSA set too low, there is no transmitting bus node)
- One optical channel is set to
“
redundant optical ring
“
mode but the second
one is not (this mode must always be set on both optical channels)
- The value for the slot time of the network is set too low
does not signal
does not signal
lit yellow
Signals are received on the RS-485 bus lines.
does not signal
CH1,
electrical
not lit
Bus node is not connected, does not signal
-Connected bus node is not turned on
- Interruption of one or both cores of the RS-485 bus line
does not signal
flashes red/lit red
Sporadic disturbances because of
- Insufficient shielding of the RS-485 bus cable
- Open bus cable, this means the RS-485 bus cable is only connected at one
end
- RS-485 segment is not terminated or only at one end
- Removal/insertion of an RS-485 bus terminal or terminating plug
Permanent problem because
- Cores A and B of the RS-485 bus cable have been swapped over
- Short circuit on the RS-485 bus cable
- Transmission time exceeded due to a bus node in a bus segment connected
to channel 1
-Module and other bus nodes connected over channel one, transmit at the
same time (e.g. because of duplicate address assignment or slot time set too
low or when restoring after segmentation in the optical line, see section 3.1.1 )
- RS-485 driver of the module defective (e.g. after lightning strike)
signals
does not signal
Mode
“
Bus with fiber-optic link monitoring
”
and
“
redundant optical ring
“
CH2, CH3
optical
lit yellow
PROFIBUS frames are received on the optical channel
does not signal
