BECKHOFF BC8000 User Manual
RS485
Bus coupler BC8000
Version: 2.3
Last change: 2006-11-06
Contents
Contents
1. Foreword 3
Notes on the documentation 3
Liability Conditions 3
Delivery conditions 3
Copyright 3
Safety Instructions 4
State at Delivery 4
Description of safety symbols 4
2. Basic information 5
Description of the BC8000 5
The Beckhoff bus terminal system 5
The interfaces 7
Power supply 7
Power supply to the power contacts 7
Power contacts 7
RS 485 Connection 9
K-bus contacts 9
Supply isolation 9
The operating modes of the bus coupler 10
Mechanical construction 11
Technical / PLC Data 13
The peripheral data in the process image 14
Starting operation and diagnostics 16
3. RS485 – Controller BC8000 18
System Introduction 18
Interface Programming 19
The Medium: Plugs and Cables 22
The User Programming Interface 23
Remanent Data 23
Persistent Data 23
4. Appendix 25
Example: Process image in the bus terminal controller 25
Representation of analog signals in the process image 27
Baud Rate Selection Table 28
Read out address 28
Programming Example 29
BC8000 as a Slave 31
General Information 31
TwinCAT as the Master 31
KS8000 as the Master 31
KS2000 Settings 32
Terminal Mapping 32
Firmware 33
5. Questions and Answers 33
General 33
No communication with the BC8x00 33
Mapping of the digital and the byte-oriented Bus Terminals onto a fixed
address 33
Drop of the digital outputs 33
Index 35
6. Support and Service 36
Beckhoff's branch offices and representatives 36
Beckhoff Headquarters 36
2 BC8000
Foreword
Foreword
Notes on the documentation
This description is only intended for the use of trained specialists in control and automation engineering
who are familiar with the applicable national standards. It is essential that the following notes and
explanations are followed when installing and commissioning these components.
Liability Conditions
The responsible staff must ensure that the application or use of the products described satisfy all the
requirements for safety, including all the relevant laws, regulations, guidelines and standards.
The documentation has been prepared with care. The products described are, however, constantly under
development. For that reason the documentation is not in every case checked for consistency with
performance data, standards or other characteristics. None of the statements of this manual represents a
guarantee (Garantie) in the meaning of § 443 BGB of the German Civil Code or a statement about the
contractually expected fitness for a particular purpose in the meaning of § 434 par. 1 sentence 1 BGB. In
the event that it contains technical or editorial errors, we retain the right to make alterations at any time
and without warning. No claims for the modification of products that have already been supplied may be
made on the basis of the data, diagrams and descriptions in this documentation.
Delivery conditions
In addition, the general delivery conditions of the company Beckhoff Automation GmbH apply.
Copyright
©
This documentation is copyrighted. Any reproduction or third party use of this publication, whether in
whole or in part, without the written permission of Beckhoff Automation GmbH, is forbidden.
BC8000 3
Foreword
i
Safety Instructions
State at Delivery
All the components are supplied in particular hardware and software configurations appropriate for the
application. Modifications to hardware or software configurations other than those described in the
documentation are not permitted, and nullify the liability of Beckhoff Automation GmbH.
Description of safety symbols
The following safety symbols are used in this documentation. They are intended to alert the reader to the
associated safety instructions..
This symbol is intended to highlight risks for the life or health of personnel.
Danger
This symbol is intended to highlight risks for equipment, materials or the
Attention
environment.
This symbol indicates information that contributes to better understanding.
Note
4 BC8000
Basic information
Basic information
Up to 64 bus terminals
each with 2 I/O channels
for any form of signal
Decentralized wiring of the
I/O level
IPC as control unit
Bus couplers for all current
bus systems
Standard C rail assembly
Modularity
BC8000 5
Description of the BC8000
The bus terminal controller BC8000 is a bus coupler with integrated PLC
functionality. The controller is programmed in IEC 1131-3. Up to 64
terminals belonging to the Beckhoff bus terminal system can be connected
to the BC8000. These include analog signal types for current and voltage,
as well as PT100 and thermocouples, in addition to digital input and output
terminals. The serial interface of the bus terminal controller can be used for
connection to additional serial devices.
The Beckhoff bus terminal system
The bus terminal system is the universal connecting link between a
fieldbus system and the sensor/actor level. A unit consists of a bus coupler,
which is the interface to the fieldbus, and up to 64 electronic terminals, of
which the last is an end terminal. Terminals, each with two I/O channels,
are available for any form of technical signal and can be combined as
desired. The various types of terminal are all constructed in the same way,
so that the planning costs are kept extremely low. The height and depth of
the construction are calculated for compact terminal cabinets.
Fieldbus technology makes it possible to use compact control
architectures. The I/O level does not need to be taken right up to the
control unit. Sensors and actors can be connected decentrally with minimal
lengths of cable. You can position the control unit at any convenient
location in the installation. Using an industrial PC as control unit makes it
possible to implement the operating and monitoring element as part of the
control hardware, so the control unit can be located on an operating desk,
control point or similar. The bus terminals constitute the decentralized
input/output level of the control unit in the switch cabinet and its
subordinate terminal cabinets. As well as the sensor/actor level, the power
unit of the equipment is also controlled via the bus system. The bus
terminal replaces a conventional terminal as the cabling level in the switch
cabinet; the switch cabinet can be made smaller.
The Beckhoff bus terminal system combines the advantages of a bus
system with the functionality of compact terminals. Bus terminals can be
used on all current bus systems and serve to reduce the diversity of parts
in the control unit, while behaving like the conventional standard units for
the relevant bus system and supporting the entire range of functionality of
the bus system.
The simple and compact assembly on a standard C rail, and the direct
cabling of actors and sensors without cross connections between the
terminals, serve to standardize the installation, as does the uniformly
designed labeling.
The small size and great flexibility of the bus terminal system mean that
you can use it anywhere that you could use a terminal and use any type of
connection – analog, digital, serial or direct sensors.
The modular construction of the terminal row, using bus terminals with
various functions, limits the number of unused channels to at most one per
function. Two channels to a terminal is the optimum solution for the number
of unused channels and the cost per channel. The possibility of using
power input terminals to provide separate power supplies also helps to
minimize the number of unused channels.
Basic information
6
6
End terminal
Potential
contacts
RS485
Supply voltage
Display of channel status
The K-bus
End terminal
Power input terminals
for
Separately powered groups
The principle of the bus
terminal
The integrated light-emitting diodes close to the sensor/actor indicate the
status of each channel.
The K-bus is the path taken by data within the terminal row. The bus
coupler carries the K bus through all the terminals by means of six contacts
on the side walls of the terminals, and the end terminal terminates the K
bus. The user does not need to know anything about the function of the K
bus or the internal operation of terminals and bus couplers. There are
numerous software tools available which provide for convenient planning,
configuration and operation.
Three power contacts pass the operating power to the following terminals.
You can use power input terminals to subdivide the terminal row as desired
into groups, each with a separate power supply. These power input
terminals are not taken into account for addressing the terminals, you can
insert them at any position along the terminal row.
You can install up to 64 terminals on a terminal row, including power input
terminals and the end terminal.
bus controller
BC 8000
for the
bus controller
feed
terminal
K bus
Additional characteristics of
the bus terminal controllers
Bus couplers for various
fieldbus systems
RS 485
0
1
9
2
8
3
7
4
5
0
1
9
2
8
3
7
4
5
0201
WD
RX
24V
0V
TX
PLC
+ +
BECKHOFF
PE PE
Power
Galvanic
isolation
Bus terminal controllers (BC) differ from bus couplers (BK) in that, in
addition to K-bus processing, a real-time PLC task is also running. Unlike
bus couplers, the signals from the terminals are processed by the PLC
task, while the fieldbus carries the in- and outputs of the PLC task. It is
possible, however, to subdivide the terminals to that some terminals are
pre-processed by the PLC task, while others are sent directly over the
fieldbus to a supervising system.
Various bus terminal controllers can be used to couple the electronic
terminal strip with integrated PLC task quickly and easily to different
fieldbus systems. It is also possible to convert to another fieldbus system at
a later time. The bus terminal controller performs all the monitoring and
control tasks that are necessary for operation of the connected bus
terminals. The operation and configuration of the bus terminals is carried
out exclusively by the bus terminal controller. Fieldbus, K-bus and I/O level
are galvanically isolated.
6 BC8000
Basic information
RS 485
RS 485
Address
If data exchange over the fieldbus fails, the PLC task continues to run as
an autonomous system.
The interfaces
There are six ways of making a connection to a bus coupler. These
interfaces are designed as plug connections and spring terminals.
Serial controller RS485 BC8000
WD
RX
TX
PLC
Power LEDs
bus coupler/power contacts
K bus
Bus coupler power supply 24 V
DC/GND
24 V DC on the topmost
terminals
Lower 3 terminal pairs for
power input
maximum 24 V
maximum 10 A
Power contacts
feeding points
selector
Power contacts
Power supply
The bus couplers need an operating power of 24 V DC which is connected
via the topmost spring terminals, labeled "24 V” and "0 V”. This power
supply serves not only the electronic components of the bus coupler but
(via the K bus) also the bus terminals. The power supply of the bus coupler
circuitry and that of the K-bus (Terminal bus) are electrically isolated from
the voltage of the field level.
Power supply to the power contacts
The six lower connections with spring terminals can be used to supply
power to the peripherals. The spring terminals are connected in pairs to the
power contacts. The power supply to the power contacts has no
connection to the power supply of the bus couplers. The power input is
designed to permit voltages up to 24 V. The pair-wise arrangement and the
electrical connection between the feed terminal contacts makes it possible
to loop through the wires connecting to different terminal points. The load
on the power contact may not continuously exceed 10 A. The current
capacity between two spring terminals is the same as the capacity of the
connecting wires.
Power contacts
Spring contacts at the side
On the right-hand side face of the bus coupler are three spring contacts
which are the power connections. The spring contacts are recessed in slots
to prevent them from being touched. When a bus terminal is connected,
the blade contacts on the left-hand side of the bus terminal are connected
to the spring contacts. The slot and key guides at the top and bottom of the
bus couplers and bus terminals ensure reliable location of the power
contacts.
BC8000 7
Basic information
8 BC8000
Basic information
Periphery level
Bus terminals
Bus coupler
24 V DC
9 pole Sub-D female
connector strip
RS 485 Connection
There is a recessed front surface on the left-hand side. A 9-pole Sub-D
connector can be plugged in here. A detailed description of the RS485
interface can be found in a further part of this manual (chapter entitled 'The
media: plugs and cable').
K-bus contacts
6 contacts at the side
3 supply groups:
fieldbus
K-bus
peripheral level
Setting up the power levels
in the bus terminal system
The connections between the bus coupler and the bus terminals are
effected by gold contacts at the right-hand side of the bus coupler. When
the bus terminals are plugged together, these gold contacts automatically
complete the connection to the bus terminals. The K bus is responsible for
the power supply to the electronic components of the K bus in the bus
terminals, and for the exchange of data between the bus coupler and the
bus terminals. Part of the data exchange takes place via a ring structure
within the K bus. Disengaging the K bus, for example by pulling on one the
bus terminals, will break this circuit so that data can no longer be
exchanged. However, there are mechanisms in place which enable the bus
coupler to locate the interruption and report it.
Supply isolation
The bus couplers operate with three independent supplies. The input
power supplies the electrically isolated K-bus circuitry in the bus coupler
and the K-bus itself. The power supply is also used to generate the
operating power for the fieldbus.
Note: All the bus terminals are electrically isolated from the K bus, so that
the K-bus is completely electrically isolated.
Terminal bus
BC8000 9
Field bus
Basic information
Power on selltest
Bus terminal test
OK
Start-up behaviour of the
bus coupler
The operating modes of the bus coupler
When it is first switched on the bus coupler carries out a self-test to check
the functions of its components and the communications of the K bus, and
while this is going on the red I/O LED will flash. When the self-test has
been completed successfully, the bus coupler will begin to test the
attached bus terminals (the "bus terminal test”) and read in the
configuration from which it constructs an internal structure list, which is not
accessible from outside. If an error occurs the bus coupler will enter the
operating mode "STOP”. If the start-up sequence is completed without
errors the bus coupler will enter the mode "fieldbus start”.
Structure list
Communication start
PLC start/
Stop
The bus coupler reports the error to the master by means of the Profibus
diagnostics. Clearing the error returns the bus coupler to its normal
operating mode.
10 BC8000
Basic information
Mechanical construction
The Beckhoff bus terminal system is remarkable for its compact
construction and high degree of modularity. When you design the
installation you will need to plan for one bus coupler and some number of
bus terminals. The dimensions of the bus couplers do not depend on the
fieldbus system. If you use large plugs, for example like some of the bus
plugs used for the Profibus, they may protrude above the overall height of
the cabinet.
Dimensions of a bus
coupler
RS 485
WD
RX
TX
PLC
The overall width of the construction is the width of the bus coupler,
including the bus end terminal, plus the width of the installed bus terminals.
The bus terminals are 12 mm or 24 mm wide, depending on their function.
Depending on the gauge of cables used the overall height of 68 mm may
be overstepped by about 5 mm to 10 mm by the cables at the front.
Assembly and link
It takes only a slight pressure to latch the bus coupler and the various bus
terminals onto a supporting 35mm C rail and a locking mechanism then
prevents the individual housings from being removed. You can remove
them without effort if you first release the latching mechanism by pulling the
orange tab. You should carry out work on the bus terminals and the bus
coupler only while they are switched off: if you plug or unplug components
while the power is on you may briefly provoke some undefined state (and,
for instance, reset the bus coupler).
You can attach up to 64 bus terminals in series on the right-hand side of
the bus coupler. When you assemble the components, make sure that you
mount the housings so that each slot comes together with the
corresponding key. You cannot make any functional connections merely by
pushing the housings together along the supporting track. When they are
correctly mounted there should be no appreciable gap between the
adjacent housings.
The right-hand side of a bus coupler is mechanically similar to a bus
terminal. There are eight connections on the top which can be used to
connect to thick-wire or thin-wire lines. The connection terminals are spring
loaded. You open a spring terminal by applying a slight pressure with a
screwdriver or other pointed tool in the opening above the terminal and you
can then insert the wire into the terminal without any obstruction. When you
release the pressure the terminal will automatically close and hold the wire
securely and permanently.
BC8000 11
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