ProSoft MVI56-PDPMV1, Руководство пользователя

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Reference MVI56-PDPMV1 ♦ ControlLogix Platform
User Manual PROFIBUS DPV1 Master
Page 200 of 251 ProSoft Technology, Inc.
5.2.1 PROFIBUS DP Architecture
The PROFIBUS DPV1 network supports multiple Master systems with several
slaves.
The following table shows the most important features of PROFIBUS DPV1:
Standard EIN 501 70
DIN 19245
Transmission equipment (Physical) EIA RS-485
IEC 1158-2 (through link or coupler)
Fiber Optic Cable (not available)
Transfer procedure Half-duplex
Bus topology Linear bus with active bus termination
Bus cable type Shielded twisted pair conductors
Connector 9-pin D-Sub
Number of nodes on the bus Max: 32 with no repeaters
Max: 125 with 3 repeaters in 4 segments
5.2.2 Bus Access
Two different bus access procedures handle the various communication
requirements for the PROFIBUS DPV1 topology:

Token Passing

Polling
Token Passing
Token passing ring is the basis for communication between the more complex,
active stations. All stations have the same rights in that a token is passed from
station to station in a logical ring. The token is passed to each station with a
maximum, definable token cycle time. A station is given transmission rights for
the duration of time that it has the token.
Master/Slave Polling
Master/slave polling guarantees a cyclic, real-time based data exchange
between the station with transmission rights, the active station, and its
subordinates, the passive stations. In this case, the Master is able to pass data to
the slave and/or receive data. The services in layer 2 (field-bus data link in ISO-
OSI reference model) organize this communication.