Siemens SIMATIC NET PROFIBUS - Manual (Page 252)

Testing PROFIBUS
A-12
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000
A.2.4 Checking the Optical Signal Quality with PROFIBUS OLM V3
The receive level of the two optical channels can be detected using a normal
commercially available voltmeter attached to measurement sockets on the
PROFIBUS OLM V3. The voltmeter can be inserted and removed during operation
using 2 mm laboratory test plugs (see Figure A-6).
Figure A-6 Testing the Signal Quality on an OLM V3 with a Voltmeter
This allows the following:
S
The incoming optical power can be documented, for example for later
measurements (aging, damage)
S A good/bad check can be made (limit value).
The correlation between the measured output voltage and the signal quality is in
the form of a curve (see Figure A-7).