Installation and Maintenance
5.7 LED Displays and Troubleshooting
SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5
37
Notes:
For a valid measurement, that the partner OLM at the other end of the fiber-optic
cable must send normal PROFIBUS frames. This can be recognized by the LED
display of the partner OLM (see section 5.7.1).
The output voltages at the measurement sockets are influenced by many factors:
¾
strength of the optical transmit power of the partner OLM
¾
ambient temperature of the optical transmitter and receiver
¾
attenuation of the transmission line
¾
transmission rate used
The measurement sockets are therefore not intended as a substitute for a
calibrated level measuring device with a calibrated light source. The value obtained
only serves to classify the received optical signals in 3 classes:
¾
good
(normal operation, green)
5V > U > 240 mV
¾
critical (optical link margin reduced, yellow)
120 mV
≤
U
≤
240 mV
¾
bad
(functionality not guaranteed, red)
U < 120 mV
The measurement must be performed with a standard ungrounded and high-
resistance voltmeter. The internal resistance of the measurement sockets is
approx. 30 k
Ω
. A connection from the measurement sockets or of reference
potential to the OLM housing is not permitted.
When an OLM of the SINEC L2FO range is connected, the OLM V4 LED level
indicator has no meaning. The measurement sockets cannot be used.
5.7
LED Displays and Troubleshooting
5.7.1
LED displays
Figure
5-13
LED displays on the front panel
Note:
The LED between
“
SYSTEM
”
and
“
CH 1
”
is unused and does not light up.
