The
INTERBUS was developed by the company Phoenix Contact. The
specification has been popular since 1987 and INTERBUS components are
available from over 200 manufacturers. INTERBUS is a fast, universal
and open sensor/actuator bus system with one master and several slaves.
Data transmission rate and expansion of the bus are independent of one
and other. The gross data transmission rate is 500kBit/s, the net data
transmission rate is 300kBit/s. For special applications with
fiber-optic cable data transmission rates of 2Mbit/s are possible. The
number of users is limited to 512.
Structure
An
INTERBUS system conforms to a ring structure. A compact strand
following one direction in the system is used for the bus connection.
Beginning at the master (PLC or IPC) the bus system connects the
respective control or computer systems to the peripheral input and
output modules. The main line of the system is called the remote bus
and bridges distances up to 12.8 km between peripheral stations. From
the remote bus, branch lines are possible. These branches can be either
be an installation remote bus or a local bus.
The
data transfer is done using the "shift register with sum framework
protocol" (in a data cycle all data is shifted through the ring).
Characteristics
FRABA Encoder with INTERBUS-Interface
The
absolute rotary encoder is a remote bus user. The individual users are
connected by an installation remote bus cable. This cable carries both
the bus line coming from the master and the return line. The connection
between the rotary encoder and the bus is made by two 9 pin connectors
(male and female). An address assignment is not necessary, since the
address of the individual users is given by their physical position on
the bus. Projecting and parameterization can for example be done with
the INTERBUS CMD software or with PC Works.
Encoder Profiles
Three
profiles are regulated by the user group ENCOM to ensure smooth data
transfer between terminals of different manufacturers:
FRABA rotary encoders can be delivered in K1, K2 and K3.
INTERBUS Loop2
To
connect single sensors and actuators in an economical way, a
transmission technology adapted for various common operating conditions
was developed. This is called INTERBUS loop. The INTERBUS loop connects
terminals to a ring with a simple two-core unshielded cable. Using
these two cores data information and voltage supply are delivered
simultaneously. The data communication takes place in the form of load
independent current signals. By this method the INTERBUS loop becomes
so interference-proof that a shielded cable is not necessary. The
coupling of the INTERBUS Loop to the INTERBUS remote bus is made by a
special bus clamp. 63 INTERBUS loop participants can be connected per
bus clamp. The successor of the INTERBUS loop, the INTERBUS loop 2
contains an integrated report and diagnostic manager and enables a
larger distance between the users in the loop. The max. distance
between the individual terminals is 20 m, the max. loop length 200 m.
INTERBUS LWL
For
applications demanding for high noise immunity or high data
transmission rates, fiber-optic cables are available as an alternative
to the conventional transmitting media. The SUPI 3 OPC (Optical
Protocol Chip) is used for these demands. It enables a distance
diagnosis and optical power adjustment for LWL transmitters. The fibre
optical cable can be easily connected to an existing INTERBUS network
with a bus clamp. Advantages of this system are high noise immunity and
also data transmission rates of up to 2 MBit/s.
