Siemens SIMATIC NET OBT User manual

SIMATIC NET
PG/PC - PROFIBUS
PROFIBUS Optical Bus Terminal
(OBT)
Operating Instructions
06/2022
C79000-G8976-C122-08
Introduction 1
Safety notices 2
Components of the product 3
Functional description 4
Network topology 5
Commissioning 6
Help with problems during
operation 7
Maintenance and
troubleshooting 8
Technical data 9
Approvals and certi󹪝cates 10

Legal information
Warning notice system
This manual contains notices you have to observe in order to ensure your personal safety, as well as to prevent damage
to property. The notices referring to your personal safety are highlighted in the manual by a safety alert symbol, notices
referring only to property damage have no safety alert symbol. These notices shown below are graded according to
the degree of danger.
DANGER
indicates that death or severe personal injury will result if proper precautions are not taken.
WARNING
indicates that death or severe personal injury may result if proper precautions are not taken.
CAUTION
indicates that minor personal injury can result if proper precautions are not taken.
NOTICE
indicates that property damage can result if proper precautions are not taken.
If more than one degree of danger is present, the warning notice representing the highest degree of danger will be
used. A notice warning of injury to persons with a safety alert symbol may also include a warning relating to property
damage.
Quali󹪝ed Personnel
The product/system described in this documentation may be operated only by personnel quali󹪝ed for the speci󹪝c
task in accordance with the relevant documentation, in particular its warning notices and safety instructions.
Quali󹪝ed personnel are those who, based on their training and experience, are capable of identifying risks and
avoiding potential hazards when working with these products/systems.
Proper use of Siemens products
Note the following:
WARNING
Siemens products may only be used for the applications described in the catalog and in the relevant technical
documentation. If products and components from other manufacturers are used, these must be recommended or
approved by Siemens. Proper transport, storage, installation, assembly, commissioning, operation and maintenance
are required to ensure that the products operate safely and without any problems. The permissible ambient
conditions must be complied with. The information in the relevant documentation must be observed.
Trademarks
All names identi󹪝ed by ® are registered trademarks of Siemens AG. The remaining trademarks in this publication may
be trademarks whose use by third parties for their own purposes could violate the rights of the owner.
Disclaimer of Liability
We have reviewed the contents of this publication to ensure consistency with the hardware and software described.
Since variance cannot be precluded entirely, we cannot guarantee full consistency. However, the information in this
publication is reviewed regularly and any necessary corrections are included in subsequent editions.
Siemens AG
Digital Industries
Postfach 48 48
90026 NÜRNBERG
GERMANY
Document order number: C79000-G8976-C122
Ⓟ 06/2022 Subject to change
Copyright © Siemens AG 2009 - 2022.
All rights reserved

Table of contents
1 Introduction ........................................................................................................................................... 5
1.1 Security information ............................................................................................................ 6
2 Safety notices ........................................................................................................................................ 9
3 Components of the product................................................................................................................. 11
4 Functional description ......................................................................................................................... 13
4.1 Interfaces .......................................................................................................................... 13
4.2 Opto-electrical signal conversion and signal regeneration................................................... 13
4.3 Supported FO 󹪝ber types.................................................................................................... 14
4.4 Displays ............................................................................................................................. 14
4.5 Operator controls............................................................................................................... 15
5 Network topology ................................................................................................................................ 17
5.1 Optical bus ........................................................................................................................ 17
5.2 Integration of long FO cable runs ....................................................................................... 18
5.3 Integrating RS-485 segments ............................................................................................. 19
6 Commissioning .................................................................................................................................... 21
6.1 Procedure for commissioning ............................................................................................. 25
6.2 Installation ........................................................................................................................ 25
6.3 Disassembly....................................................................................................................... 30
7 Help with problems during operation ................................................................................................ 31
7.1 Help with problems during operation ................................................................................ 31
8 Maintenance and troubleshooting ...................................................................................................... 33
9 Technical data...................................................................................................................................... 35
10 Approvals and certi󹪝cates ................................................................................................................... 39
Index .................................................................................................................................................... 45
PROFIBUS Optical Bus Terminal (OBT)
Operating Instructions, 06/2022, C79000-G8976-C122-08 3

Table of contents
PROFIBUS Optical Bus Terminal (OBT)
4Operating Instructions, 06/2022, C79000-G8976-C122-08

Introduction 1
The PROFIBUS OBT (Optical Bus Terminal) it is a network component used in optical PROFIBUS DP
󹪝eldbus networks. It allows the connection of either a single device without an integrated optical
interface or an RS-485 segment to the optical PROFIBUS DP. The following 󹪝gure shows an
example of a con󹪝guration.
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Figure 1-1 Example of an optical PROFIBUS DP con󹪝guration
Connections
The connection between the individual bus nodes takes the form of an optical bus with two-
󹪝ber plastic 󹪝ber-optic cables (plastic 󹪝ber-optic cables are also known as POF, Polymer Optical
Fiber) or PCF 󹪝ber-optic cables (PCF = Polymer Cladded Fiber, synonymous with HCS1 󹪝ber-optic
cable). Since 󹪝ber-optic cables (FO cable) are completely insensitive to EMC interference,
complex grounding concepts and protection measures are unnecessary. This also applies to the
laying of a equipotential bonding cables. Due to be opto-electronic conversion, there is
automatically electrical isolation so that potential di󹪜erences as can occur in extensive plants are
no longer noticed.
PROFIBUS Optical Bus Terminal (OBT)
Operating Instructions, 06/2022, C79000-G8976-C122-08 5

1) HCS is a registered trademark of Spectran Speciality Optics and stands for "Hard Polymer
Cladded Silica Fiber".
Sensitivity
Just as the FO cable is insensitive to EMC interference, an FO cable also emits no electromagnetic
waves into its environment. Sensitive electronic devices located in the vicinity of the 󹪝ber-optic
cable therefore need no additional protection or suppression measures.
Power supply
The OBT requires an operating power supply of 24 VDC that is connected via two screw terminals.
Operating state
LEDs signal the current operating state and any problems a󹪜ecting operation.
Mechanical construction
The mechanical construction consists of a compact plastic housing that can be mounted either
on a DIN rail or any 󹪞at surface.
Security information
1.1 Security information
Siemens provides products and solutions with industrial security functions that support the
secure operation of plants, systems, machines and networks.
In order to protect plants, systems, machines and networks against cyber threats, it is necessary
to implement – and continuously maintain – a holistic, state-of-the-art industrial security
concept. Siemens’ products and solutions constitute one element of such a concept.
Customers are responsible for preventing unauthorized access to their plants, systems,
machines and networks. Such systems, machines and components should only be connected to
an enterprise network or the internet if and to the extent such a connection is necessary and only
when appropriate security measures (e.g. 󹪝rewalls and/or network segmentation) are in place.
For additional information on industrial security measures that may be implemented, please
visit
https://www.siemens.com/industrialsecurity (https://www.siemens.com/industrialsecurity).
Siemens’ products and solutions undergo continuous development to make them more secure.
Siemens strongly recommends that product updates are applied as soon as they are available
and that the latest product versions are used. Use of product versions that are no longer
supported, and failure to apply the latest updates may increase customer’s exposure to cyber
threats.
Introduction
1.1 Security information
PROFIBUS Optical Bus Terminal (OBT)
6Operating Instructions, 06/2022, C79000-G8976-C122-08

To stay informed about product updates, subscribe to the Siemens Industrial Security RSS Feed
under
https://www.siemens.com/cert (https://www.siemens.com/cert).
Device defective
If a fault develops, send the device to your SIEMENS representative for repair. Repairs on-site are
not possible.
Recycling and disposal
The products are low in pollutants, can be recycled and meet the requirements of the WEEE
directive 2012/19/EU for the disposal of electrical and electronic equipment.
Do not dispose of the products at public disposal sites.
For environmentally friendly recycling and the disposal of your old device contact a certi󹪝ed
disposal company for electronic scrap or your Siemens contact (Product return (https://
support.industry.siemens.com/cs/ww/en/view/109479891)).
Note the di󹪜erent national regulations.
Trademarks
The following and possibly other names not identi󹪝ed by the registered trademark sign ® are
registered trademarks of Siemens AG:
SCALANCE, C-PLUG, OLM
Introduction
1.1 Security information
PROFIBUS Optical Bus Terminal (OBT)
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Introduction
1.1 Security information
PROFIBUS Optical Bus Terminal (OBT)
8Operating Instructions, 06/2022, C79000-G8976-C122-08

Safety notices 2
Read the safety notices
Note the following safety notices. These relate to the entire working life of the device.
CAUTION
To prevent injury and damage, read the manual before using the device.
Safety notices on use in hazardous areas
General safety notices relating to protection against explosion
WARNING
EXPLOSION HAZARD
Do not open the device when the supply voltage is turned on.
Safety instructions for use in hazardous locations according to UL/FM HazLoc
If you use the device under UL or FM HazLoc conditions, you must also adhere to the following
safety instructions in addition to the general safety instructions for protection against explosion:
This equipment is suitable for use in Class I, Division 2, Groups A, B, C and D or non-hazardous
locations only.
This equipment is suitable for use in Class I, Zone 2, Group IIC or non-hazardous locations only.
PROFIBUS Optical Bus Terminal (OBT)
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Safety notices
PROFIBUS Optical Bus Terminal (OBT)
10 Operating Instructions, 06/2022, C79000-G8976-C122-08

Components of the product 3
Supplied
• 1 x PROFIBUS OBT
• 1 x Operating instructions (Compact) A5E03345735-01
Not supplied
• Plastic 󹪝ber-optic cables, sold in meters
• Assembly tool for 󹪝ber-optic cable connectors
• Operating Instructions for the PROFIBUS OBT
• Fiber-optic cable connectors
PROFIBUS Optical Bus Terminal (OBT)
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Components of the product
PROFIBUS Optical Bus Terminal (OBT)
12 Operating Instructions, 06/2022, C79000-G8976-C122-08

Functional description 4
The OBT is a repeater with 3 channels.
4.1 Interfaces
The OBT has the following interfaces for connection of PROFIBUS DP segments:
• Channel 1 (CH1) is an electrical RS-485 interface. It is designed as a 9-pin D-sub female
connector. A PROFIBUS DP node or a PC, PG, OP or an RS-485 segment can be connected to
the OBT via this channel. The copper segment should be kept as short as possible since this
can couple in disturbances into the optical PROFIBUS DP.
• Channel 2 (CH2) and channel 3 (CH3) are optical interfaces. These are designed as duplex
female connectors. The end a two-󹪝ber plastic or PCF 󹪝ber-optic cable 󹪝tted with two simplex
male connectors is connected to each of these duplex female connectors.
The OBT also has a 3-pin terminal for connection of the 24 V power supply and, if necessary, a
ground cable.
4.2 Opto-electrical signal conversion and signal regeneration
The OBT converts the RS-485 level received at channel 1 into an optical signal level that is output
via channels 2 and channel 3.
Signals received at channel 2 or 3 are converted to electrical signals and
• output on channel 1 as an electrical signal
• they are then converted into an optical signal again and output on the other optical channel.
There is no echo on the receive channel; in other words, received signals are not sent back on the
same channel.
The OBT regenerates the signals in amplitude and time. This makes it possible to cascade up to
126 modules in an optical bus. The cascading depth is simply limited by the monitoring times of
the connected devices.
The latency per OBT is 6 bit times.
PROFIBUS Optical Bus Terminal (OBT)
Operating Instructions, 06/2022, C79000-G8976-C122-08 13

4.3 Supported FO 󹪝ber types
The OBT supports the 󹪝ber types listed in the following table:
Table 4-1 Achievable FO cable distance between the two devices on optical PROFIBUS DP
Fiber type Link length between 2 devices
Plastic FO cable 980/1000 μm with 2 󹪝bers and
max. max. 200 dB/km cable attenuation
0.1 to 50 meters
PCF FO cable 200/230 μm with 2 󹪝bers and max.
max. 10 dB/km cable attenuation
0 to 300 meters
The speci󹪝ed link length between the devices assumes that the partner devices use the same
optical components as the OBT. This is, for example, the case with the IM 153–2 FO and IM 467
FO.
The transmission speed is not dependent on the 󹪝ber type used or the cable length. This can be
up to 12 Mbps.
The following accessories are available:
• Plastic 󹪝ber-optic cable (sold in meters), connectors/polishing set and the assembly tool for
plastic 󹪝ber-optic cable
The plastic 󹪝ber-optic cables do not have connectors 󹪝tted. The plastic simplex connectors
can be 󹪝tted easily on site with the available tools.
• PCF FO cable (preassembled)
PCF cables with 4 PCF simplex connectors 󹪝tted are available in 󹪝xed lengths.
4.4 Displays
The OBT has 4 LEDs to display the operating state.
L+ 24 V (green)
not lit: Power supply missing or internal power supply is defective or short-
circuited
󹪞ashes: Power supply present, transmission speed not yet set
lit green: Transmission speed set, power supply functioning correctly
CH1, CH2 , CH3 (channel 1 to 3, yellow)
not lit: Data is not being received
lit yellow: Data is being received
Functional description
4.4 Displays
PROFIBUS Optical Bus Terminal (OBT)
14 Operating Instructions, 06/2022, C79000-G8976-C122-08

Figure 4-1 LEDs on the front panel
4.5 Operator controls
The OBT itself does not have any controls. The only point to remember is that the PROFIBUS
connecting cable connected to channel 1 (does not ship with product) needs to be terminated
at both ends.
Functional description
4.5 Operator controls
PROFIBUS Optical Bus Terminal (OBT)
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Functional description
4.5 Operator controls
PROFIBUS Optical Bus Terminal (OBT)
16 Operating Instructions, 06/2022, C79000-G8976-C122-08

Network topology 5
5.1 Optical bus
Along with other SIMATIC devices such as the IM 153–2 FO or IM 467 FO, OBTs are connected
to optical PROFIBUS DP to form an optical bus.
PROFIBUS DP bus nodes with an RS-485 interface are connected to channel 1 of the OBT via bus
connectors and a PROFIBUS bus cable. The bus segment must be terminated at both ends.
The OBT can be used at any point on the optical bus. If it is used at the start or end, the unused
optical channel must remain closed with the rubber plug. This prevents contamination of the
optical elements and disturbances caused by incident light.
The connection on an optical bus is made using two-󹪝ber plastic FO cable (max length 50 m) or
PCF FO cable (max. length 300 m). The FO cables have two simplex connectors 󹪝tted at both
ends.
The FO connection between two devices is established by the optical transmitter of one device
being connected to the optical receiver of the other device via a 󹪝ber, while the optical receiver
of the 󹪝rst device is connected to the optical transmitter of the other (crossover cable).
If an OBT or a 󹪝ber-optic cable fails, the network is split into two separate networks. Depending
on the location of the problem, devices are no longer accessible.
Note
If problems are detected on the electrical interface, there is a segmentation, in other words, the
frames are not forwarded. The segmentation is canceled when the problem has been
eliminated. In this case, it is assumed that a minimum number of error-free frames were received
on the electrical channel. The segmentation is also canceled when no frames are received for at
least 1 second. In this case, it is assumed that unplugging the PROFIBUS connector caused
problems and that there are no more nodes on the electrical channel.
The OBT does not support the establishment of single-󹪝ber rings or redundant ring structures.
PROFIBUS Optical Bus Terminal (OBT)
Operating Instructions, 06/2022, C79000-G8976-C122-08 17

5.2 Integration of long FO cable runs
The maximum permitted length of PCF FO cable with the OBT is 300 m. If longer FO links or other
FO cable types, for example glass graded index 󹪝bers or monomode 󹪝bers are necessary, they
can be used by combining OBTs with OLMs (Optical Link Module). In this situation, the OBT is
connected electrically with the OLM (OBT/CH 1 to OLM/CH 1) and the OLM is connected to the
long FO cable link. At the end of the FO cable link, the combination is reversed with a second
OLM/OBT pair.
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Figure 5-1 Example of covering longer FO links with OBTs and OLMs
The maximum permitted transmission speed and the type and maximum length of the FO cable
link is decided by the OLM type.
Network topology
5.2 Integration of long FO cable runs
PROFIBUS Optical Bus Terminal (OBT)
18 Operating Instructions, 06/2022, C79000-G8976-C122-08

5.3 Integrating RS-485 segments
The OBT allows the attachment of a PROFIBUS RS-485 segment.
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Figure 5-2 Example of the integration of RS-485 segments
Network topology
5.3 Integrating RS-485 segments
PROFIBUS Optical Bus Terminal (OBT)
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Network topology
5.3 Integrating RS-485 segments
PROFIBUS Optical Bus Terminal (OBT)
20 Operating Instructions, 06/2022, C79000-G8976-C122-08