Siemens SIMATIC NET PROFIBUS OBT, Manual

Page: 21 / 38

Installation and Startup
5-5
PROFIBUS Optical Bus Terminal (OBT)
C79000-G8976-C122-03
Instructions for Connectoring Plastic Fiber - Optic Cables (with photos)
You can download a detailed instruction brochure with photos illustrating how to
connector plastic fiber - optic cables from the Internet:
German: http://www.ad.siemens.de/csi/net
English: http://www.ad.siemens.de/csi_e/net
Select SEARCH on this page and enter the number 574203 in the Entry ID box
and start the search.
Connecting the Power Supply
PE M
L+
NEC CLASS2
24VDC, 200 mA
Figure 5-3 Layout of the Terminal Block - Ground Terminal PE and Power Supply
Terminals M, L+
The power supply for the PROFIBUS OBT must be a stabilized safety extra-low
voltage complying with IEC 950 / VDE 0805, m18 V and maximum
+32 V (typ24 V). The power source must meet the specifications of NEC
class 2 to comply with the UL/CSA approval. The unit is intended to be installed
on the load side of the class 2 or class 3 power source as defined by the
National Electric Code (NEC), Article 725 - 2
The module must be wired correctly according to the National Electrical code
(NEC) complying with NEC Article 725 - 52, 725 - 54, 725 - 61 and 725 - 71.
If the PROFIBUS OBT is not installed on a grounded rail, a grounding
conductor with a cross-section of 2.5 mm
2
should be connected from the PE
terminal to the nearest possible ground point.