PROFIBUS-DP field bus
PCD0
26/766 E2
(HB_PCD0 26 766_E2.DOC)
SAIA-Burgess Controls Ltd.
Page 167
13
PROFIBUS-DP field bus
PROFIBUS was designed in 1983 as an open field bus, standardized
in 1991 (DIN 19 245) and became a European standard in 1996 (EN
50 170).
PROFIBUS-DP has been specially designed for production
automation with remote periphery.
When planning a system not only local/building regulations must be
met which mainly define the location of machines and field devices,
but also physical regulations for a PROFIBUS system in accordance
with EN 50 170.
Field-specific installation instructions of the various suppliers and
safety-specific guidelines for a system remain in force.
13.1
PROFIBUS-DP bus topology
According to PROFIBUS-RS485 specification a maximum of 32 slaves
can be connected to a bus segment. To operate more PROFIBUS-DP
slaves the system must be segmented using repeaters.
Repeaters provide an electrical connections between bus segments
and ensure that data signals are amplified and refreshed. Repeaters
can be used in addition to isolating bus segments or bus part sections.
A repeater adds another bus segment with full line length and the
maximum number of field devices that can be connected to a
PROFIBUS system. Repeaters will cause signal delays. This must be
taken into account when the system is configured.
Key:
Repeater with terminating
resistor
Repeater without
terminating resistor
Slave with terminating
resistor
Slave without
terminating resistor