Prosoft-technology MVI69-PDPMV1 Manual de usuario descargar pdf (Pagina 161)

MVI69-PDPMV1 ♦ CompactLogix or MicroLogix Platform Reference

PROFIBUS DPV1 Master User Manual

ProSoft Technology, Inc. Page 161 of 225

July 8, 2011

6.2.1 Bus Access

Two different bus access procedures handle the various communication

requirements for the PROFIBUS DPV1 topology:

 Token Passing

 Polling

6.2.2 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.

6.2.3 Master/Slave Communication Phases

The communication between the Master and the slaves is split up into the

following phases:

 Parameterization and configuration phase

 Usable data transfer phase

Before a DP slave can be integrated into the usable data transfer phase, the

parameterization and configuration phase runs a device identification test that

verifies that the planned configuration matches the actual device configuration for

each slave in the PROFIBUS network. The test verifies that:

 the device is actually there

 it is the right type of device

 the address, which is set on the device, matches the station address on the

bus

 the formats, telegram length information, and bus parameters are correct

and

 the number of configured inputs and outputs is correct.

6.2.4 Communication Types

In addition to point-to-point data transfer, the PROFIBUS protocol can also

handle the following types of communication.

 Broadcast communication:

An active node sends an unacknowledged message to all other nodes

(Master and slaves)

 Multicast communication (control instructions)

An active node sends an unacknowledged message to a group of nodes

(Master and Slaves)

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Prosoft-technology MVI69-PDPMV1 Manual de usuario Pagina 161