Installation and Maintenance
5.7 LED Displays and Troubleshooting
SIMATIC NET PROFIBUS, Optical Link Module
40
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5
5.7.2.2
Error display on CH1
Check whether
¾
the DIL switch S0 is in position 1, when the OLM is in the electrical star
segment of a star topology (see section 3.2)
¾
the problem remains after removing the RS-485 connector.
Still there: Device defective
4
. Change the OLM.
Gone: The error is in the RS-485 bus segment.
Check:
–
all RS-485 connectors as described in section 5.3
–
the setup and the shielding of the RS-485 bus segment.
–
the RS-485 bus segment using the PROFIBUS bus monitor
–
the configuration of all bus nodes.
5.7.2.3
Error display on CH2 / CH3
1. Check whether
¾
only modules of the same type are connected to each other optically (see
chapter 3),
¾
the optical fiber is permitted for the module type being used and does not
exceed the permitted length (see
Table 2-1
).
¾
the optical channels connected via fiber-optic cables are set to the same mode.
(see section 4.2.3)
¾
the ends of the fiber-optic cables and the optical transmission and receiving
components are clean
¾
the fiber-optic cable connectors are connected completely and correctly,
¾
the requirements of section 5.1.2 were met when connecting and laying the
optical bus cables.
2. Detect the optical receive level (section 5.6):
¾
Check the fiber-optic cable attenuation with an optical level meter if the level is
in the range
“
function not guaranteed
”
or
“
optical link power margin reduced". If
the attenuation is too high, replace the fiber-optic cable. If the attenuation is
within the valid range, one of the two OLMs of the disturbed segment is
defective. First, replace the OLM which supplies the signal for the measurement
mentioned above. If the problem remains, replace the other OLM instead. If
there is no optical level meter at hand, you can still get an idea of where the
problem lies simply by swapping over both fiber-optic cables at both OLMs: if
the problem moves along with the cables, the cable is almost certainly faulty, if
it does not, the problem is in one of the OLMs.
¾
If the level is in the range
“
normal operation
”
, first check the transmitting OLM,
as described above, and then the receiving OLM, if necessary.
4
Does not apply if the monomaster of a PROFIBUS network is connected to the RS-485 bus segment to be tested. In this case,
swap the suspect OLM with another OLM from the network and then carry out the test mentioned above.
If the error moves with the OLM, the device is defective. Replace the OLM.
If the error does not move with the OLM, the disturbance originates in the RS-485 bus segment. Take measures as described
above.
