Siemens AS 488/TM manual Bus connector, Electrical bus terminal, Optical link module

This catalog is out of date, see note on page 3

Possible bus configurations: Linien-, Stern- und Ringstruktur bei gemischt elektrisch/optischen Netzen

You can find further information and conditions on the PROFIBUS in the Catalog IK PI "Industrial communications and field devices".

■Configuration

The electrical PROFIBUS network can be configured with a mul- tipoint or tree structure. The most important features of the elec- trical network are:

•High-quality bus cable

•RS 485 transmission procedure (according to EIA)

•Bus connector (alternative: bus terminals) for connection of PROFIBUS stations

•Simple, uniform mounting and earthing concept

•Simple installation

The electrical network can also be operated together with an op- tical PROFIBUS network. The optical network can be configured with optical link modules OLM in a multipoint, ring or star struc- ture. The most important features of the optical network are:

Bus communication

PROFIBUS-TM

PROFIBUS-TM

Bus connector

The bus connector can be used to directly connect the stations on the PROFIBUS together in loop-through mode. The connector is easy to mount, and has an integral terminating resistor.

With the AS 388/TM automation system, the bus connector is plugged onto the IF 964 interface module on the EXM 378-2 module; with the AS 488/TM automation system, it is plugged onto the IF 964 interface module of an EXM 478 extension mod- ule.

An optical link module OLM can also be connected to the bus connector.

The bus connectors are available with a pivoted or axial cable outlet, in each case with degree of protection IP 20.

The standard connection for PROFIBUS-TM in the AS 488/TM automation system is the interface module in the second exten- sion module. However, an interface module in the first extension module can also be used if vacant, and if the interface assign- ment in the initialization files is adapted.

Electrical bus terminal

The RS 485 bus terminal is used if a variable design is desired for the bus connections. The bus terminal is snapped onto a DIN rail for assembly. As the result of a selectable, integral ter- minating resistor, no additional installation is required.

Note:

The total length of the bus terminal spur lines per segment (max. 200 m PROFIBUS cable) can be up to 10 m; i.e. max. 6 bus ter- minals are permissible for the recommended bus terminals with

1.5m spur line; additional stations must be connected using bus connectors. The PROFIBUS design guidelines must be ob- served (see SIMATIC NET manual "PROFIBUS networks" (6GK1 970–5CA20–0AA0).

Optical link module

PROFIBUS networks can be configured with the optical link modules OLM in a multipoint, ring or star structure. They permit high availability by means of a redundant power supply and re- dundant cables.

•High availability for redundant optical ring with OLM

•Wide range

•Cascading of OLMs possible

•Insensitive to electromagnetic interferences

•Electrical isolation

The solution with optical link modules is more appropriate than the electrical network for signal transmission over longer dis- tances, and is insensitive to overvoltages, e.g. resulting from lightning. The equipotential bonding which is required when us- ing an electric two-wire cable between two buildings for operator safety according to VDE 0100 can also be omitted in this case.

•Either glass or plastic fiber-optic cables

•High degree of adaptation to local conditions

Recommendation:

Independent of the technical possibilities, we recommend that you use one optical link module OLM per station (AS/OS/ES) for availability reasons.

Up to 41 OLMs can be connected in series permitting a distance of 21 km to be covered at the used data transmission rate of 1.5 Mbit/s and the resulting max. cable length of 530 m.

When using a CS-L2 bridge, the max. number of OLMs in a ring is reduced to 32, and the covered distance to 16 km.

There are several designs of OLM (see Catalog IK PI); the type OLM/G12 for glass fiber-optic cables, 4-channel design, 6GK1 502-3CB10 is recommended for use with TELEPERM M, and also permits the design of redundant rings.

Siemens PLT 112 · 2002 9/3