Siemens ST PCS 7 User Manual

PROFIBUS DP

Siemens ST PCS 7 · November 2007

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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).

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FastConnect Stripping Tool

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

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.

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.

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 

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 AG 2007