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5
Overview of PROFIBUS
Section 1-1
The three masters form a logical token ring. When an active station receives
the token message, it can perform its master role for a certain period of time.
During this time it can communicate with all assigned slave stations in a mas-
ter-slave communication relationship, and a DPM2 master can take the initia-
tive to communicate with DPM1 master stations in a master-master
communication relationship.
Multi-peer communication
In addition to logical peer-to-peer data transmission, PROFIBUS-DP provides
multi-peer communication (broadcast and multicast).
Broadcast communication
In the case of broadcast communication a master station sends an unac-
knowledged message to all other stations (masters and slaves).
Multicast communication
In the case of multicast communication a master station sends an unacknow-
ledged message to a predetermined group of stations (masters and slaves).
1-1-5
Diagnostic functions
Extensive Diagnostics
Extensive diagnostic functions defined in PROFIBUS-DP enable the fast loca-
tion of error at slave devices. Diagnostic messages are transmitted over the
bus and collected at the master. Three levels of diagnostic messages are
defined:
Device Related
Diagnostics
• Messages concerning the general operational status of the whole device,
e.g. over temperature, low voltage.
Module Related
Diagnostics
• Messages indicating that an error is present in a specific I/O range of a
station, e.g. an 8-bit output module.
Channel Related
Diagnostics
• Messages indicating an error at a given input or output, e.g. short circuit
on Output 5.
DPM1
DPM2
DPM 1
Token Passing
Polling
PROFIBUS
Passive stations
Slave devices
Active stations
M aster devices
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...