![background image](http://html1.mh-extra.com/html/omron/sysmac-cj1w-prm21/sysmac-cj1w-prm21_operation-manual_743083017.webp)
3
Overview of PROFIBUS
Section 1-1
• Layer 7, the Application Layer of this model, defines the application func-
tions. This Layer is only applicable to PROFIBUS-FMS.
OSI Layer 1, 2 and user
interface
PROFIBUS-DP uses layers 1 and 2, and the user interface. Layers 3 to 7 are
not defined for PROFIBUS-DP. The User interface Layer defines the interface
functions for specific application areas, i.e. the PROFIBUS-DP basic functions
and communication profiles.This streamlined architecture ensures fast and
efficient data transmission. The application functions which are available to
the user, as well as the system and device behaviour of the various PROFI-
BUS-DP device types, are specified in the user interface.
OSI Layer 1: Transmission
medium
RS-485 transmission technology or fibre optics are available for transmission.
RS-485 transmission is the most frequently used transmission technology. Its
application area includes all areas in which high transmission speed and sim-
ple inexpensive installation are required. PROFIBUS modules are intercon-
nected by single twisted-pair shielded copper wires.
RS-485 technology
The RS-485 transmission technology is very easy to handle. Installation of the
twisted pair cable does not require expert knowledge. The bus structure per-
mits addition and removal of stations or step-by-step commissioning of the
system without influencing the other stations. Later expansions have no effect
on stations which are already in operation.
RS-485 Transmission
speed
Transmission speeds between 9.6 kbit/s and 12 Mbit/s can be selected as
shown in the table below. One unique transmission speed must selected for
all devices on the bus (master and slave devices) when the system is com-
missioned
Cable length
The maximum cable length values depend on the transmission speed and are
based on type-A cable (see
). The length can be increased by the
use of repeaters.However, it is not recommended to use more than three
repeaters in series in a PROFIBUS network.
DP-Profiles
DP-Extensions
User Interface Layer
DP Basic Functions
(7) Application Layer
(6) Presentation Layer
(5) Session Layer
NOT DEFINED
(4) Transport Layer
(3) Network Layer
(2) Data Link Layer
Fieldbus Data Link (FDL)
(1) Physical Layer
RS485 / Fibre Optics
Baud rate (kbit/s)
Distance / segment (m)
9.6
1200
19.2
1200
45.45
1200
93.75
1200
187.5
1000
500
400
1500
200
3000
100
6000
100
12000
100
Содержание SYSMAC CJ1W-PRM21
Страница 2: ...iv...
Страница 36: ...22 Basic Operating Procedure Section 1 5...
Страница 52: ...38 Defining PROFIBUS DP in the Software Section 2 5...
Страница 112: ...98 Allocated CIO Area Words Section 4 2...
Страница 122: ...108 Command Response Reference Section 5 2...
Страница 160: ...146 Replacing the Unit Section 7 8...
Страница 174: ...160 Appendix...
Страница 180: ...166 I O Data Conversions Appendix D...
Страница 186: ...172 Configurator Error and Warning Messages Appendix E...
Страница 187: ...173 Index...
Страница 188: ...174 Index...
Страница 190: ...176 Revision History...