Siemens OLM/P11 V4.0, OLM/G12 V4.0, OLM/G11-1300 V4.0, OLM/P12 V4.0, OLM/G12-1300 V4.0 Operating Instructions Manual

Preface

1

Introduction

2

Network Topologies

3

Product Characteristics

4

Installation and Maintenance

5

Approvals and Marks

6

References

7

Drawings

8

SIMATIC NET PROFIBUS
Optical Link Module
OLM / P11 V4.0
OLM / P12 V4.0
OLM / P11 V4.0
OLM / G12 V4.0
OLM / G12-EEC V4.0
OLM / G11-1300 V4.0
OLM / G12-1300 V4.0

Operating Instructions

07/2008

A2B00065774O, Edition V1.5

Copyright Siemens AG 2008. All rights reserved.
The reproduction, transmission or use of this document or its contents is not permitted
without express written authority. Offenders will be liable for damages. All rights, including
rights created by patent grant or registration of a utility or design, are reserved.

Disclaimer
We have checked the contents of this manual for agreement with the hardware and
software described. Since deviations cannot be precluded entirely, we cannot guarantee
full agreement. However, the data in this manual are reviewed regularly and any
necessary corrections included in subsequent editions.

Siemens AG
Automation and Drives
Postfach 4848, D-90327 Nürnberg

Siemens AG 2008
Subject to technical change

Siemens Aktiengesellschaft A2B00065774O, Edition V1.5

Safety Guidelines

These operating instructions contain notices which you should observe to ensure your own personal safety as
well as to avoid property damage. The notices referring to your personal safety are highlighted in the manual by a
safety alert symbol, notices referring to property damage only have no safety alert symbol. Depending on the
danger level, the notices are displayed in descending order as follows.

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

with safety alert symbol indicates that minor personal injury can result if proper precautions are not taken.

Caution

without safety alert symbol indicates that property damage can result if proper precautions are not taken.

Notice

used without the safety alert symbol indicates a potential situation which, if not avoided, may result in an
undesirable result or state.

When several danger levels apply, the notices of the highest level (lower number) are always displayed. If a
notice refers to personal damages with the safety alert symbol, then another notice may be added warning of
property damage.

SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

iii

Qualified Personnel

The device/system may only be set up and operated in conjunction with this documentation. Only qualified
personnel should be allowed to install and work on the equipment. Qualified persons are defined as persons
who are authorized to commission, to ground, and to tag circuits, equipment, and systems in accordance with
established safety practices and standards.

Correct Usage of Hardware Products

Please note the following:

Warning

This device may only be used for the applications described in the catalog or the technical description, and only in
connection with devices or components from other manufacturers which have been approved or recommended by
Siemens. This product can only function correctly and safely if it is transported, stored, set up, and installed
correctly, and operated and maintained as recommended.

Note: If PROFIBUS OLMs are supplied via long 24 V supply lines or over networks, measures must be taken
to prevent interference by strong electro magnetic pulses on the supply lines. These can occur, for example,
due to lightning strikes or when heavy inductive loads are switched. The robustness of the PROFIBUS OLM
against electromagnetic interference was verified by the Surge Immunity Test according to EN61000-4-5. For
this test, overvoltage protection for the voltage supply lines is necessary. The Dehn Blitzductor VT AD 24V
Type no. 918402 or a comparable protection element is, for example, suitable. Manufacturer: DEHN+SÖHNE
GmbH+Co.KG Hans Dehn Str.1 Postfach 1640 D-92306 Neumarkt, Germany

Brands

All names which are labeled with the trademark symbol ® are registered trademarks of Siemens AG. Third
parties using for their own purposes any other names in this document which refer to trademarks might
infringe upon the rights of the trademark owners.

SIMATIC NET PROFIBUS, Optical Link Module

iv Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

1

Preface ...................................................................................................................................................... 1

1.1 Preface...........................................................................................................................................1

2 Introduction................................................................................................................................................ 3

2.1 Introduction ....................................................................................................................................3

3 Network Topologies................................................................................................................................... 7

3.1 Linear (bus) Topology ....................................................................................................................8

3.1.1 Linear (bus) topology with fiber-optic link monitoring and segmentation.......................................9

3.1.2 Bus topology without fiber-optic link monitoring.............................................................................9

3.2 Star Topology...............................................................................................................................10

3.3 Ring Topology..............................................................................................................................12

3.3.1 Redundant Optical Ring with two OLMs ......................................................................................14

4 Product Characteristics............................................................................................................................ 17

4.1 Technical Specifications ..............................................................................................................17

4.2 Installation ....................................................................................................................................20

4.2.1 Safety related notices ..................................................................................................................20

4.2.2 General information on commissioning .......................................................................................21

4.2.3 Setting compatibility, mode and transmit power ..........................................................................22

5 Installation and Maintenance ................................................................................................................... 27

5.1 Installation ....................................................................................................................................27

5.1.1 Installation instructions.................................................................................................................27

5.1.2 Connecting optical cables ............................................................................................................30

5.2 Installation of the Modules ...........................................................................................................31

5.3 Connection of the Electrical RS-485 Bus Cables ........................................................................33

5.4 Connecting of the Operating Power Supply.................................................................................35

5.5 Connecting the Signaling Contact Wires .....................................................................................35

5.6 Receive Level of the Optical Channels........................................................................................36

5.7 LED Displays and Troubleshooting .............................................................................................37

5.7.1 LED displays ................................................................................................................................37

5.7.2 Troubleshooting ...........................................................................................................................39

5.8 Maintenance.................................................................................................................................41

5.9 Cleaning .......................................................................................................................................41

5.10 Configuration................................................................................................................................42

5.10.1 Configuring optical bus and star topologies.................................................................................42

5.10.2 Configuring redundant optical rings .............................................................................................42

6 Approvals and Marks............................................................................................................................... 45

6.1 CE Mark .......................................................................................................................................45

6.2 c-tick.............................................................................................................................................46

6.3 FM approval ................................................................................................................... ..............47

Contents

SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

v

6.4 Ex approval ..................................................................................................................................47

6.5 UL approval (U.S. and Canada)...................................................................................................47

6.6 Shipbuilding approvals.................................................................................................................48

7 References .............................................................................................................................................. 49

7.1 References..................................................... ..............................................................................49

8 Drawings.................................................................................................................................................. 51

Tables

Table 2-1

Number of electrical and optical ports per module, .......................................................................4

Table 4-1 Overview of the product characteristics .......................................................................................19

Table 4-2 DIL-switches in compatibility mode..............................................................................................23

Table 5-1 Meaning of the LED displays and indication by the signaling contact.........................................39

Table 5-2 Constants for calculating the slot time for DP-standard (redundant optical ring) ........................43

Table 5-3 Constants for calculating the slot time for DP/FMS (”universal“) and DP with S5 95U (redundant

optical ring)...................................................................................................................................43

Figures

Figure 2-1

PROFIBUS OLM with position of all interfaces, displays and adjustment options ........................3

Figure 3-1 Network structure in a linear (bus) optical topology.......................................................................8

Figure 3-2 Network structure with an optical star topology ...........................................................................10

Figure 3-3 Network structure with a redundant optical ring topology............................................................12

Figure 4-1 View of the OLM module from the top .........................................................................................21

Figure 5-1 Measures to suppress..................................................................................................................27

Figure 5-2 Securing shielded cables with cable clamps and cable retainers...............................................28

Figure 5-3 View of the module from below....................................................................................................30

Figure 5-4 Installation of a module on a standard DIN rail............................................................................31

Figure 5-5 Installation of a module with a mounting plate.............................................................................32

Figure 5-6 Drilling measures for the mounting plate, all dimensions are millimeter......................................33

Figure 5-7 Electrical port, connector assignment D-sub jack.......................................................................33

Figure 5-8 Operating power supply, pin assignment 5-pin terminal block ..................................................35

Figure 5-9 Signaling contact relay with floating contacts; ............................................................................35

Figure 5-10 Signaling contact, pin assignment 5 pin terminal block.............................................................35

Figure 5-11 Position of the level recording connections ................................................................................36

Figure 5-12 Relationship between measured output voltage and signal quality.............................................36

SIMATIC NET PROFIBUS, Optical Link Module

vi Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

Figure 5-13 LED displays on the front panel...................................................................................................37

SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

1

1 Preface

1

1.1 Preface

Purpose of the operating instructions

These operating instructions support you when commissioning PROFIBUS OLM devices
(Optical Link Module)

Validity of these operating instructions

These operating instructions are valid for the following devices:

SIMATIC NET OLM/P11 V4.0 6GK1 503-2CA00

SIMATIC NET OLM/P12 V4.0 6GK1 503-3CA00

SIMATIC NET OLM/G11 V4.0 6GK1 503-2CB00

SIMATIC NET OLM/G12 V4.0 6GK1 503-3CB00

SIMATIC NET OLM/G12-EEC V4.0 6GK1 503-3CD00

SIMATIC NET OLM/G11-1300 V4.0 6GK1 503-2CC00

SIMATIC NET OLM/G12-1300 V4.0 6GK1 503-3CC00

Convention

G 1 -1300

G glass fiber
P plastic fiber

OLM/ 2

Number of RS-485 interfaces

optional: wavelength

Number of optical interfaces

Preface

1.1 Preface

SIMATIC NET PROFIBUS, Optical Link Module

2 Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

Further documentation

You will find more information on other SIMATIC NET products that you can use with the
OLM V4.0 devices in the “SIMATIC NET PROFIBUS networks SIEMENS AG” manual.

Finding information

To help you find the information you require more quickly, the manual includes not only the
table of contents but also the following sections in the Appendix:

• Glossary

• Index

Audience

These operating instructions are intended for persons involved in the commissioning of
PROFIBUS networks with the link modules of the OLM V4.0 series.

Standards and approvals

The devices of the OLM V4.0 series meet the requirements for the CE mark. For detailed
information, please refer to chapter 6 of these operating instructions.

The devices of the OLM V4.0 series also meet the requirements for the UL, C-Tick, FM and
ATEX marks. For detailed information please refer to chapter 6 of these operating
instructions.

The devices of the OLM V4.0 series also meet several requirements for shipbuilding. For the
respectively valid approvals call our hotline [phone].

Furthermore you can gather information at:

http://support.automation.siemens.com

SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

3

2 Introduction

2

2.1 Introduction

This section provides you with an overview of the functions of the PROFIBUS OLM4.0
product family.

What is possible?

PROFIBUS OLMs are designed for use in optical PROFIBUS fieldbus networks. They
allow the conversion of electrical PROFIBUS interfaces (RS-485 level) into optical
PROFIBUS interfaces and vice versa.
The modules can be integrated in existing PROFIBUS fieldbus networks with the known
advantages of optical transmission technology. A complete PROFIBUS fieldbus network
can also be set up with modules in a linear (bus), star or ring topology as well as any
combination of these topologies.
To increase the reliability of the fieldbus network in case of failure, the redundant ring is
supported.

Figure 2-1 PROFIBUS OLM with position of all interfaces, displays and adjustment options

LED displays

Channel 1
RS-485

DIL switch fo

r

modes

Operating voltage

Signaling contact

Sockets for
measuring levels of
the optical interfaces
(see section 5.6).

Channel 2 Channel 3
Optical channels

Introduction

2.1 Introduction

SIMATIC NET PROFIBUS, Optical Link Module

4 Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

Every module has two (OLM P11, G11) or three (OLM P12, G12) independent channels
(ports) that consist of transmitter and receiver pairs.
The power supply voltage for operation is 24 V DC. To increase operational reliability, a
redundant power supply is possible.

The electrical channel is designed as 9-pin D-sub socket. An RS-485 bus segment
complying with PROFIBUS standard EN 50170 /2/ can be connected to this channel.
The fiber-optic cables are connected via BFOC

1

/2.5 connectors.

Six multicolor LEDs indicate the current mode and any disruptions as well as the level
ratios on the optical interfaces.

Table 2-1 shows the different connection options of the modules and the maximum
possible optical range of the single channels.

OLM/ P11 P12 G11 G12

G12-EEC

G11-1300 G12-1300

Number of channels

-electrical

-optical

1

1

1

2

1

1

1

2

1

1

1

2

Fiber types that can be used

- plastic fiber-optic cables

980/1000 µm

- PCF fiber-optic cables

(HCS

®

)

200/230 µm

- silica glass fiber-optic cables

10/125 µm (9/125µm)

50/125 µm

62.5/125 µm

80 m

400 m

-

-

-

80 m

400 m

-

-

-

-

-

-

3 km

3 km

-

-

-

3 km

3 km

-

-

15 km

10 km

10 km

-

-

15 km

10 km

10 km

Table 2-1 Number of electrical and optical ports per module,
usable fiber types, as well as maximum achievable fiber-optic cable distances between the modules.

See the “Technical Data” for precise conditions of use. PCF stands for Polymer Cladded Fiber and is
similar to HCS

®

2.

There is a measurement output available for every channel, at which the optical input
level can be measured with a standard voltmeter.

The various error and disruption messages of the OLM are available as a group signal via
a signaling contact (relay with floating contacts) for further processing. The individual
modes as well as error/fault messages are displayed by several multicolor LEDs on the
front panel of the device (see section 5.7.1).

The mechanical design consists of a compact and stable metal housing which can be
mounted either on a DIN rail or on a mounting plate.

The modules are configured using switches that are easily accessible from the outside.

1

BFOC stands for Bayonet Fiber Optic Connector.

This type of connector is functionally compatible with ST connectors.
ST is a registered trademark of the company AT&T.

2

HCS

®

is a trademark of Ensign-Bickford Optics Company.

Introduction

2.1 Introduction

SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

5

The PROFIBUS OLMs comply with the standard EN 50170 /2/ and with the technical
guideline “Optical transmission technology for PROFIBUS” published by the PROFIBUS
User Organization (PNO).

OLM/G12 and OLM/G12-EEC have the same functions. They only differ in the
specification of the ambient climatic conditions: the OLM/G12 is suitable for use in the
standard temperature range from 0 °C to 60 °C, whereas the OLM/G12-EEC (extended
environmental conditions) can be used in the extended temperature range of -25 °C to
+60 °C and up to 100% humidity (condensing).

Network Topologies

2.1 Introduction

SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

7

3 Network Topologies

3

Which network topologies can be implemented?

The following network topologies can be implemented with the PROFIBUS OLM:

• Point-to-point connection

• Bus (linear) topology

• Star topology

• Redundant optical ring

Combinations of these basic types are also possible. To set up the fiber-optic links
of these network topologies, cables with two optical fibers are used.

If a high degree of availability is required of the fieldbus network, this can be
increased by using a redundant network configuration, for example to allow
continued communication if a cable is broken.

Please note the following:

¾ Single DTEs or complete PROFIBUS segments with a maximum of 31 nodes

can be connected to the electrical interface of the PROFIBUS OLM.

¾ Use only fiber-optic cables in areas subject to heavy noise to avoid EMC

problems affecting the entire network.

¾ Only OLMs of the same wavelength may be connected to each other optically:

– OLM/P11 and OLM/P12 with each other

– OLM/G11 and OLM/G12 as well as OLM/G12 EEC with each other

– OLM/G11-1300 and OLM/G12-1300 with each other

¾ Optical channels connected via fiber-optic cables must be set to the same mode.

¾ Transitions between different OLM types are only possible via the RS-485

interface.

¾ In the network topologies described below, the OLM/G12-EEC can be used

everywhere where an OLM/G12 can be used.

Network Topologies

3.1 Linear (bus) Topology

SIMATIC NET PROFIBUS, Optical Link Module

8 Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

3.1 Linear (bus) Topology

Figure 3-1 Network structure in a linear (bus) optical topology

In a linear or bus structure, the single PROFIBUS OLMs are connected by two-fiber
cables.
At the beginning and at the end of a line, modules with one optical channel are
adequate, in-between modules with two optical channels are necessary.

If single point-to-point connections are required, they can be implemented with
modules with one optical channel each.

The bus topology can be implemented with and without fiber-optic link monitoring.
Fiber-optic link monitoring is recommended in homogeneous OLM networks
(factory default).

Please note that to ensure correct operation, the following conditions must be kept
to when configuring the network:

¾ The parameter MIN TSDR, described in the PROFIBUS standard EN 50170 /2/,

must be set to a value ≥ 11 on all DTEs. This is usually the case but should be
checked if permanent communication problems occur.

¾ Choose bus node addresses as low as possible when configuring your network,

to reduce master timeouts that may occur due to disruptions.

You will find information on changing the setting in the documentation supplied by
the manufacturer of your DTE.

Ch 1

Ch 2

SE

OLM/P11

OLM/G11(-1300)

Ch 1

Ch 2

SE

OLM/P11

OLM/G11(-1300)

Ch 1

Ch 2
SE

Ch 3

SE

OLM/P12

OLM/G12(-1300)

Ch 1

Ch 2

SE

Ch 3

SE

OLM/P12

OLM/G12(-1300)

DTE/

bus segment

DTE/

bus segment

DTE/

bus segment

DTE/

bus segment

FOC

RS-485

Network Topologies

3.1 Linear (bus) Topology

SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

9

3.1.1 Linear (bus) topology with fiber-optic link monitoring and segmentation

Use this mode especially when you want a disrupted fiber-optic cable segment to
be separated from the rest of the network (see section 4.2.2.4). Only use this
mode, if you only connect PROFIBUS OLM V4.0 or V3/V4.0 with each other.

Monitoring mechanisms:

• Send echo: yes

• Monitor echo: yes

• Suppress echo: yes

• Monitor: yes

• Segmentation: yes

In this mode, the individual fiber-optic links are monitored by the two connected
modules.

If a module fails or a fiber-optic cable breaks or disturbances are detected on the
optical transmission line, the fiber-optic link between the two OLMs is interrupted
(segmented). The PROFIBUS network is separated into two (sub)networks each
remaining functional on its own. The problem is indicated by the channel LEDs
changing to red and by the signaling contacts of the two OLMs connected to the
disturbed fiber-optic link. The segmentation is canceled automatically as soon as
both modules recognize that the segmented fieldbus (sub)network is no longer
disrupted based on test frames that they send out automatically. Note that if a
problem occurs in networks with several active bus nodes, two logical token rings
are formed. As a result, temporary network disturbances may occur due to double
tokens or frame collisions when the full network is restored.

Note:

If modules with two optical channels are used at the end of a line, the unused
optical channel must be set to the mode “bus without fiber-optic link monitoring”,
so that it does not cause a broken fiber-optic cable signal (see section 4.2.3.4).
Remember that the optical channels that are not connected must be protected
against external light and pollution by protective caps.

3.1.2 Bus topology without fiber-optic link monitoring

Use this mode when you connect a PROFIBUS OLM with a different fiber-optic
component according to the PROFIBUS guideline (optical/electrical converter),
which does not send a frame echo and does not expect or tolerate a frame echo.

Monitoring mechanisms:

• Send echo: no

• Monitor echo: no

• Suppress echo: no

• Monitor: no

• Segmentation: no

In this mode, there is no monitoring of the individual fiber-optic links.

Network Topologies

3.2 Star Topology

SIMATIC NET PROFIBUS, Optical Link Module

10 Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

3.2 Star Topology

Figure 3-2 Network structure with an optical star topology

Several modules are grouped together to form an active PROFIBUS star coupler.
Further modules are connected to this via two-core fiber-optic cables. The modules
of the star coupler are interconnected via the electrical channel (electrical star
segment). All OLM types for different fiber-optic cables (plastic, PCF, glass) can be
combined via the electrical star segment.

Please note the following:

¾ CH1 must be set to “Monitor off” (S0 = 1) on all OLMs connected to the

electrical star segment. This disables segmentation function of the RS-485
channel of this OLM to achieve high availability of the electrical star.

¾ Make sure that the electrical star segment is carefully wired. Keep its span as

small as possible to avoid interference in the electrical star segment that can
spread to the whole network. You can achieve this by positioning the OLMs
directly next to each other on a DIN rail.

¾ Switch on the terminating resistors (see section 5.3) in the bus connectors at the

two ends of the electrical star segments.

¾ If possible do not connect any bus nodes to the electrical star segment.

To set up an active PROFIBUS star coupler, modules with one or two optical
channels can be used. To connect a DTE or an RS-485 bus segment to an active
star coupler, modules with one optical channel are adequate.

FOC

RS-485

Ch 1

Ch 2

SE

OLM/P11

Ch 1

Ch 2SECh 3

SE

OLM/G12

Ch 1

Ch 2

SE

OLM/G11-1300

Ch 1

Ch 2

SE

OLM/P11

Ch 1

OLM/P11

Ch 2

S

E

Ch 1

OLM/G11

Ch 2

S

E

Ch 1

OLM/G11-1300

Ch 2

S

E

Ch 1

OLM/P11

Ch 2

S

E

Ch 1

OLM/G11

Ch 2

S

E

DTE/

bus segment

DTE/

bus segment

DTE/

bus segment

DTE/

bus segment

DTE/

bus segment

Electrical star segment

Network Topologies

3.2 Star Topology

SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

11

When the monitoring on the optical channels is active, the fiber-optic links are
monitored by the connected OLMs.

Note:

Unused optical channels you intend to use later to expand the network cause a
broken fiber-optic cable signal if the monitoring is active. You can avoid this error
message by setting unused channels to the mode “bus without fiber-optic link
monitoring”. Remember that the optical channels that are not connected must be
protected against external light and pollution by protective caps.

Network Topologies

3.3 Ring Topology

SIMATIC NET PROFIBUS, Optical Link Module

12 Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

3.3 Ring Topology

Figure 3-3 Network structure with a redundant optical ring topology

This network topology is a special form of the bus topology. “Closing” the optical
bus achieves high operational reliability in the network. A redundant optical ring
can only be implemented using modules with two optical channels.

Monitoring mechanisms:

• Send echo: yes

• Monitor echo: yes

• Suppress echo: yes

• Segmentation: yes

The interruption of one or both fiber-optic cables between the modules is detected
by the OLM and the ring becomes an optical bus.

If one module fails, only the DTEs connected to this module or the RS-485
segment are disconnected from the ring. The rest of the network itself stays
functional as a bus. The problem is indicated by the LEDs of the two OLMs
connected to the disrupted fiber-optic link and by the signaling contacts of these
OLMs. The segmentation is canceled automatically as soon as both modules
recognize that the segmented fieldbus (sub)network is no longer disrupted based
on test frames that they send out automatically. The bus then closes again to form
a ring.

Ch 1

Ch 2

SE

Ch 3

SE

OLM/P12

OLM/G12(-1300)

Ch 1

Ch 2
SE

Ch 3

SE

OLM/P12

OLM/G12(-1300)

Ch 1

Ch 2

SE

Ch 3

SE

OLM/P12

OLM/G12(-1300)

DTE/

bus segment

DTE/

bus segment

DTE/

bus segment

DTE/

bus segment

FOC

RS-485

Ch 1

Ch 2

SE

Ch 3

SE

OLM/P12

OLM/G12(-1300)

Network Topologies

3.3 Ring Topology

SIMATIC NET PROFIBUS, Optical Link Module
Operating Instructions, 07/2008, A2B00065774O, Edition V1.5

13

Please note the following:

For correct operation, the following conditions must be met:

¾ Only use this mode, if you only connect PROFIBUS OLMs with at least version

V3 with each other. Both optical channels must be set to the “redundant optical
ring” mode on all PROFIBUS OLMs. All modules within a ring must be connected
to each other over fiber-optic cables. There must be no RS-485 bus cable within
the ring.

¾ The MIN TSDR parameter described in the PROFIBUS standard EN 50170 /2/

must be set to a value ≥ 11 on all DTEs. This is usually the case but should be
checked if permanent communication problems occur.

¾ Choose bus node addresses as low as possible when configuring your network,

to reduce master timeouts that may occur due to disruptions.

¾ If there is a failover (for example due to a cable break), there is failover time

during which correct data transmission is not possible. To ensure bumpless
bridging for the application, it is advisable to set the frame retry number on the
PROFIBUS master to at least 3. To ensure a bumpless return from the optical
bus to the optical ring once a problem has been eliminated, there must be no
frame on the network at this time. This status occurs when the master sends a
GAP query to an address lower than HSA. The master tries to address the
device cyclically and waits for a reply at the longest until the configured slot time
has elapsed (“GAP query”). The OLM recognizes this status and closes the
optical bus to form an optical ring in the middle of this query sequence. This
results in the following two important configuration requirements for the
redundant optical ring:

 The value of the parameter HSA (Highest Station Address) must be set on

all DTEs so that there is at least one address between bus address 0 and
the value HSA that is not occupied by a bus node, in other words there is at
least one address gap. You can create this address gap simply by setting
the HSA value one higher than the highest existing bus node address.

Notice

If this requirement is not or no longer met, the optical bus will no longer close to form a redundant
optical ring after segmentation. In this case the error message

(LED and signaling contact) of the two

affected OLMs will not be cleared after eliminating the problem.

 The slot time must be set to about twice the value compared with a

redundant network. See section 5.10 for further information. You will find
information on changing the setting in the documentation supplied with your
DTE or with the configuration software.

Notice

No glass fiber-optic cable may be connected to an OLM that uses plastic fiber-optic cable and vice
versa.