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26 •
INTERBUS
The INTERBUS transmission log can be understood as a large shift register.
Each slave, with its input and output data, bus position, and data width, is an
integral part of this shift register. Input and output data are processed simulta-
neously during a scan cycle. The master receives input data from the end of
the data ring as it enters output data into the shift register. Each slave receives
data at its input, and outputs it to the next slave, thus acting as a bus repeater.
Each INTERBUS slave receives its address automatically, based on its physi-
cal position in the bus system. Control signals (CLOCK, RESET, SELECT,
CONTROL) permit the monitoring of each individual slave.
Each slave has an ID register (identification register) containing information
about the type of module, the number of I/O addresses, and status and fault
conditions.
INTERBUS recognizes two operating modes:
1. ID cycle
2. Data cycle
7.2 Module Properties
The ID code of the I/O module and the data length as an INTERBUS slave is
determined by the electronic module.
Type
Remote bus unit
In the ID cycle, the fieldbus controller board reads the ID register of each
device contained in the bus system and compiles the process image table on
the basis of this information. The ID cycle is used for initialization and
needs a request to become active.
In the data cycle, the input data of each device is transmitted to the master,
and the output data is transmitted from the master to each device.
ID code
0x03
Data length
32 Bit
The data length of the module is extended to 32 bit by the diagnostic
information masked into the process data.
Fieldbus Dependent I/O Module
INTERBUS
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