Siemens ST PCS 7 manual Electrical networks, FastConnect, Repeater for Profibus, RS 485-iS coupler

© Siemens AG 2007

Communication

PROFIBUS DP

■Overview

Shielded twisted-pair cables are used as the transmission me- dium for electric PROFIBUS DP networks. The PROFIBUS DP stations are connected to these bus lines through a bus connec- tor (max. 32 stations per segment).

■Design

FastConnect Stripping Tool

FastConnect

PROFIBUS FastConnect is a system for fast and easy assembly of PROFIBUS copper cables. The system comprises compatible components:

•FastConnect Standard Cable for fast assembly

•FastConnect Stripping Tool

with FastConnect Blade Cassettes (spare blade cassettes for the stripping tool)

•FastConnect bus connector for PROFIBUS

Repeater for PROFIBUS

A repeater links the individual bus segments with RS 485 tech- nology. Main applications are:

•Increase in number of nodes and distances

•Electrical isolation of segments

If diagnostics functions for physical cable diagnostics are re- quired in addition to the standard repeater functionality, a diag- nostics repeater can be alternatively used. It additionally per- forms physical online monitoring of the copper bus cables. In the event of a fault it sends a diagnostic message with detailed in- formation about the type and location of the fault to the DP mas- ter.

Electrical networks

Active RS 485 terminating element

The active RS 485 terminating element is used to terminate bus segments. The component supplied with 24 V DC independent of the bus stations provides a defined RS 485 signal level, and suppresses reflections on the line. Bus stations (e.g. ET 200S) can be coupled and decoupled without feedback to/from PROFIBUS networks terminated by active RS 485 terminating elements.

RS 485-iS coupler

The RS 485-iS coupler is an isolating transformer with which the PROFIBUS DP fieldbus can be routed intrinsically-safe into the hazardous area.

The RS 485-iS coupler has the following functions:

•Connection of intrinsically-safe PROFIBUS DP stations, e.g. ET 200iSP, ET 200iS or devices from other vendors with Ex i DP connection

•Conversion of the electrical PROFIBUS DP RS 485 transmis- sion technology into the intrinsically-safe RS 485-iS transmis- sion technology with a transmission rate of 1.5 Mbit/s

•Suitable as a safety barrier

•Additional use as a repeater in the hazardous area.

The RS 485-iS coupler as an open unit can only be used in hous- ings, cabinets or rooms for electrical equipment. It is assembled on a SIMATIC S7-300 rail which can be positioned horizontally or vertically.

The RS 485-iS coupler is integrated into the PROFIBUS as fol- lows:

• Connection to standard PROFIBUS DP via standard Sub-D
socket (at the bottom on the RS 485-iS coupler, behind the	9
right front door).
• Connection of PROFIBUS DP with RS 485-iS transmission

technology via screw terminals (at the top of the RS 485-iS coupler, behind the right front door)

• The last bus station on the intrinsically-safe PROFIBUS DP segment (not further RS 485-iS couplers) must be terminated by a selectable resistance using the connector, Order No. 6ES7 972-0DA60-0XA0.

Siemens ST PCS 7 · November 2007

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