Rockwell Automation 2711 PanelView 550/900 Profibus Communications User Guide - Manual (Page 15)

PROFIBUS DP Communications 15
Publication 2711-6.3
Command Word
The management of the multiplex module data exchange is
performed by the DP Master’s program. The first word of the
multiplex output module contains handshake information and is used
to initiate a data block exchange.
The command word has the following structure:
Handshake Bit
Reserved Bit
The Block In field is 7 bits wide and specifies which input block
(1..127) is to be returned from the PanelView terminal’s database.
A value of 0 indicates no multiplex input block is requested.
The Block Out field is 7 bits wide and specifies the output block
(1..127) that is being sent to the PanelView terminal’s database.
A value of 0 indicates no multiplex output block is being sent.
The Handshake Bit is set to 1 by the DP Master to indicate to the
PanelView terminal that a new multiplex data exchange has been
initiated. A later section describes the handshake operation in detail.