PROFIBUS DPV1

PROFIBUS DPV1 refers primarily to the read and write telegrams, with which data sets in the slave are acyclically accessed. A distinction between a Class 1 (C1) and a Class 2 (C2) master is also made for DPV1. The acyclic Class 1 or Class 2 connections differ in that the acyclic C1 connection is established with the DP startup of the cyclic DP mode. Acyclic DPV1 C1 read and write telegrams can be sent from the master to the slave from the state WAIT-CFG of the slave. In contrast, the C2 connection is established separately, usually by a second C2 master. For example, a manufacturer-specific project configuration and diagnostics tool can access the slave data independent of the cyclic DP connection.

When two masters are used, however, is must always be borne in mind that these share bus access (a token is exchanged), so that time relationships are less favorable than in the case of a single master system.