Rockwell Automation 2711 PanelView 550/900 Profibus Communications User Guide - Manual (Page 12)

PROFIBUS DP Communications 12
Publication 2711-6.3
The following sections describe how data exchange occurs on a
PROFIBUS DP network.
PanelView Data Exchange Modules with DP Master
The PanelView always exchanges the following four blocks when
configured by the Generic Electronic Data Sheet (.GSD):
•
Real Time Output Module
•
Real Time Input Module
•
Multiplex Output Module
•
Multiplex Input Module
Each module is 16 words in length. Real Time and Multiplex
modules are continually exchanged with the PROFIBUS DP Master.
Details of configuring the PanelView terminal, building PanelView
applications, and implementing the multiplex module handshake
mechanism will be covered in later sections.
When communication begins, the PROFIBUS DP Master sends the
DP slave bus parameter data and information on the expected
PROFIBUS DP slave’s module configuration. After receiving the
data, the PROFIBUS DP slave compares this information to its
actual configuration. If the DP Master’s information does not
exactly match the slave’s actual configuration an error is reported by
the PanelView and no communications occur (refer to
troubleshooting section).
PanelView and DP Master Databases
The PanelView database consists of up to 128 input and 128 output
blocks. Block 0 is 16 words in length and blocks 1 to 127 are 15
words in length. When communication occurs over a PROFIBUS
DP network, these blocks are transferred into and out of the various
PanelView data exchange modules. Blocks and Modules are
associated as follows:
•
Output Block 0 is associated with the Real Time Output Module
•
Input Block 0 is associated with the Real Time Input Module
•
Output Blocks 1 to 127 are associated with the Multiplex Output
Module
•
Input Blocks 1 to 127 are associated with the Multiplex Input
Module
PROFIBUS DP Data
Exchange