BECKHOFF BC2000 - Manual (Page 9)

Basic Principles
BC2000 8
Power contacts
Spring contacts on the side On the right hand face of the bus terminal controller there are three spring
contacts for the power contact connections. The spring contacts are hidden
in slots so that they can not be accidentally touched. By attaching a bus
terminal the blade contacts on the left hand side of the bus terminal are
connected to the spring contacts. The tongue and groove guides on the top
and bottom of the bus terminal controllers and of the bus terminals
guarantees that the power contacts mate securely.
Fieldbus connection
Beckhoff Lightbus
Fibre optic ring
Beckhoff Z1000 connector
There is a recessed front face on the left hand side. The typical Beckhoff
Lightbus connector can be inserted here. The Beckhoff Lightbus consists
of an optical fibre ring into which the bus terminal controller is inserted.
Here the plug out of which red light shines when the Beckhoff Lightbus is
switched on is inserted into the upper socket. On the figure this is labelled
with „IN“. Optical fibre connectors of type Beckhoff Z1000 are required for
the connection.
Configuration and Programming Interface
Serial interface under the
front cover The bus terminal controllers have an RS232 interface at the bottom of the
front face. The miniature connector can be joined to a PC with the aid of a
connecting cable and the KS2000 configuration software. The interface
permits the bus terminals to be configured, for example adjusting the
amplification factors of the analogue channels. The interface can also be
used to change the assignments of the bus terminal data to the process
image in the bus terminal controller. The functionality of the configuration
interface can also be reached via the fieldbus using string communication
facility.
This interface is also used for programming the BC2000. The cable for the
interface is supplied along with TwinCAT BC.
Terminal Bus Contacts
6 contacts on the side
In order to connect the bus terminal controller to the bus terminals, the bus
terminal controller has gold contacts on the right hand side. When the bus
terminals are pushed together the gold contacts automatically make the
connection between the bus terminals. The voltage supply to the terminal
bus electronics in the bus terminals and the data exchange between the
bus terminal controller and the bus terminals is carried out by the terminal
bus. A part of the data exchange takes place via a ring structure within the
terminal bus. Opening the terminal bus, e.g. by pulling out one of the bus
terminals, opens the ring. Data exchange is no longer possible. Special
mechanisms nevertheless allow the bus terminal controller to identify the
location of the interruption and to report it.
Galvanic isolation
3 potential groups:
Field bus
Terminal bus (K bus)
Peripheral level The bus terminal controllers operate by means of three independent
potential groups. The supply voltage feeds the terminal bus electronics in
the bus terminal controller and the terminal bus itself, which is electrically
separate. The supply voltage is also used to generate the operating
voltage for the fieldbus.
Remark: All the bus terminals are galvanically isolated from the terminal
bus. The terminal bus is thus galvanically isolated from everything else.