Siemens SIMATIC NET PROFIBUS User Manual

24

4 Setting Up

Version 1.0 8/00

4.4 Installation

The receiving level of the two optical Ports CH2 and CH 3
can be measured using a conventional voltmeter con-
nected to the measuring sockets. The voltmeter can be
connected and disconnected while the module is in
operation without any interference using 2 mm laboratory
test plugs. 
The OLM is protected against short circuits at the measu-
ring sockets, although data transmission may be briefly
disrupted*.

With this 
– the incoming optical performance can be documented,

e.g. for later measurements (ageing, damage) 

– a good/poor check can be carried out (limit value).

Further information can be found in Appendix 8.4
”Measuring sockets“ p.35.

* Only an ungrounded, high-resistance voltmeter may be

used to take measurements.
The reference potential socket may not be connected to
the OLM housing.

Measuring sockets

Reference potential

Pin assignment, 5-pin terminal block: 
terminals F1 and F2.

Always ensure that the pins are correctly assigned at
the 5-pin terminal block. Make sure that the connecting
leads of the signaling contacts are adequately insula-
ted, particularly if you are working with voltages greater
than 32 V. Incorrect assignment can lead to destruction
of the module.

L1+ / +24 V

F1

M /    

F2

L2+ / +24 V*