BECKHOFF BK2000 - Manual (Page 10)

Basic information
10 BK2000
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. The clear dimensions of the bus coupler are not exceeded
thanks to the use of fiber-optic cable with the Z1000 connectors.
Dimensions of a bus
coupler
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 connections
It takes only a slight pressure to latch the bus coupler and the various bus
terminals onto a supporting 35 mm 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.