GE Industrial Solutions EntelliGuard TU Trip Units - Manual (Page 65)

DEH-4567B EntelliGuard TU Trip Units: UL/ANSI Models
Profibus Communication
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SECTION 9. PROFIBUS COMMUNICATION
DEFINITIONS
Profibus DP (Process Field Bus): An open standard based
on EN 50170 for field bus communication with DP
communication protocol. DP variant (decentralized
periphery) is the high-speed communication. Profibus DP
allows cyclic data transfer only between the automation
device (master) and the peripheral devices in a network.
The cyclic data transfer involves parameters, metering, and
diagnostic, analog, and alarm data. See Table 4-12 for a
complete list of cyclic telegrams.
Profibus DPV1: An extension of the DP protocol, which in
addition to the cyclic communication, provides acyclic
communication for parameterization, alarm, diagnostic,
analog, RTC control, and control of the slaves.
A Profibus DP slave: Any peripheral device, such as GTU
DP, which processes information and sends its output to
the Profibus class 1 and/or class 2 master. It must comply
with EN 50 170 standard, Volume 2, Profibus.
Class 1 master: The main controller for the high-speed
data exchange with its Profibus slave devices that is
usually a programmable logic controller (PLC) or a PC
running Profibus base logic.
GSD: A device data (GSD), which is provided by GE on its
website, that has the operational characteristic of the GTU
DP. It provides the system with an easier means to change
communication options, diagnostic, metering among other
parameters.
PROFIBUS SYSTEM CONCEPT
The figure on the right shows the communication network
system overview consisting of: Profibus class 1 master (PLC
or PC), with cyclic data exchange GTU which are Profibus
DP slaves.
Figure 9-1: Profibus Communication Network
PROFIBUS DP-PARAMETERIZATION
The GTUsupports parameterization. The relay keeps its user
parameter data / setpoints in a non-volatile memory and
does not need device related parameterization during
startup of the DP master.
GTU can be parameterized via Profibus Class 1 using
Profibus parameterized service. In this case only default
configurations are allowed.
COMMUNICATION SETUP AND STATION ADDRESSES
The Profibus-DPV1 basic configuration has one DP master
and one DP slave. In a typical bus segment up to 32
stations can be connected (a repeater has to be used if
more than 32 stations operate on a bus). The end nodes on
a Profibus- DP network must be terminated to avoid
reflections on the bus line.
During projecting of the bus structure ensure that the bus
line is segmented dependent upon the length of the branch
lines, the maximum cable length, and the number of bus
stations. The allowable lengths are dependent upon
transmission speeds and are specified in the Profibus
standard DIN 19245-3 and in other publications dealing
with this topic.