BECKHOFF BK7500 - Manual (Page 21)

SERCOS interface Coupler BK7500
BK7500 21
SERCOS interface Coupler BK7500
Introduction to the SERCOS Interface
System
The SERCOS interface (Serial Real-time Communication System) has
become established round the world in the numerical controller sector. The
BK7500 now also permits connection to the sensor / actuator level.
Its high real-time performance, and the interference immunity of the optical
fibre technology are important features of this bus system.
The BK7500 Lightbus is designed for fast data exchange at the sensor /
actuator level. Central control devices (such as, for example,
programmable logic controllers) communicate here over a fast serial
connection with distributed input and output devices. Data is exchanged
with these distributed devices cyclically. The central controller (master)
reads the input information from the slaves (drive telegram) and sends the
output information to the slaves (master data telegram).
A high data throughput is not in itself sufficient for successful use of a bus
system. Ease of handling, good diagnostic facilities and secure
transmission technology are also of the utmost importance if the user’s
demands are to be satisfied.
System configurations and
device types A single-master system can be implemented with the SERCOS interface. A
maximum of 254 slaves can be connected to one bus.
A BK7500 is a peripheral device (sensor/actuator) that reads input
information and passes output information on to the peripherals. It is also
possible to have device configurations that only handle either input or
output information. Typical Beckhoff Bus Terminals are binary
inputs/outputs for 24V or 230V, analog inputs, analog outputs, counters,
incremental encoders etc. The quantity of input and output information is
device-dependent, and is limited in the BK7500 to 32 bytes of input data
and 32 bytes of output data.