Siemens CS 275 manual Bus components, technical data, Technical data

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Design

Bus components, technical data

Overvoltage protection

The participants connected to the remote bus can be exten- sively protected against destruction by overvoltages by means of the coarse and fine overvoltage protection units.

The coarse protection limits high-voltage signals of high power to the arc voltage. The coarse protection is able to handle brief peaks in the kA range. It is installed where the remote bus cable enters the building. The fine protection reduces the residual voltage which passes the coarse protection down to a value between the internal conductor and the screen of the remote bus cable which is harmless for the amplifier of the inductive coupler in the bus converter. The fine protection is fitted on the connector board AF.

Remote bus cable

Standard coaxial cable is used as the remote bus cable. This may be routed in potentially explosive atmospheres to

DIN 57 165/VDE 0165, Section 5.6.1. It is also suitable for burial in the ground. The max. permissible length is 4000 m.

An in-house cable with smaller outer diameter and smaller per- missible bending radius can be used indoors. The max. permis- sible length is 2000 m.

An increased tensile strength up to 25 000 N is possible using a cable with additional armouring. If protection against damage by rodents and mechanical damage is required, the cable with additional steel-tape armouring should be used.

Connection of remote bus cables

It may be necessary when using remote bus cables to connect sections together. The maximum available length of the in-house cable is 200 m, with all other types of cable 1000 m.

The type of connection depends on the type of cable. Standard and in-house cables are connected by splicing or by using RF plugs. The 2 other types of cable can be connected by splicing.

To provide protection against mechanical damage, the connec- tion should be enclosed in a metal sleeve. The cable armouring can be electrically connected using a copper cable (e. g. as additional overvoltage protection) and secured to prevent ten- sion. The sleeve is filled with sealing compound following as- sembly. All parts required can be obtained as a parts kit for splicing coaxial cables.

Technical data

Number of participants	100, dependent on bus loading
Distance without bus coupler	Max. 4000 m
Data formats	Variable
Bus control	Distributed (token passing principle)
Data protection	Block parity
Hamming distance	d = 4
Noise immunity	IEC Recommendation 255-4
Local bus
Number of participants	Max. 9
	(bus converter UI counts as
	participant)
Tranmission rate	250 kbit/s
	The transmission rate is increased to
	340 kbit/s with autonomous local bu-
	ses, i. e. without remote bus coupling
Data transfer rate	Up to 2800 analog values/s or
	up to 38400 binary values/s or
	a corresponding combination
Overall cable length between
participant interface modules	Max. 20 m
Standard cable	12 x 2 x 0.22 m2
Signal transmission	Unbalanced
Signal level	5 V
Signal form	Unipolar
Coupling	Open collector
Redundant local bus	Standard
Remote bus
Number of converters (UI)	Max. 32
Number of bus couplers	Max. 7,
	max. 2 between 2 communication
	subscribers
Transmission rate	250 kbit/s
Standard cable	2YC (mS) CY 1.6/10-75
	(Z2/5) vs sw
Signal form	Bipolar current signals
Coupling	Inductive, non-reactive
Redundant remote bus	Option

Siemens PLT 130 . 1994 3/5