Rockwell Automation 2711 PanelView 550/900 Profibus Communications User Guide - Manual (Page 16)

PROFIBUS DP Communications 16
Publication 2711-6.3
Status Word
The first word of the multiplex input module contains handshake
status information from the PanelView terminal. The status word
indicates the progress of a multiplex module data exchange to the DP
Master. In addition, the status word is read–only to the DP Master.
The status 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 being returned from the PanelView terminal’s database.
A value of 0 indicates no multiplex input block is being returned.
This can happen for two reasons: 1) no multiplex input block was
requested, or 2) the multiplex input block requested does not exist in
the PanelView terminal’s database.
The Block Out field is 7 bits wide and specifies the output block
(1..127) that was sent to the PanelView terminal’s database. A value
of 0 indicates two possible events: 1) no multiplex output block was
sent, or 2) the multiplex output block sent does not exist in the
PanelView terminal’s database.
The Handshake Bit is set to 1 by the PanelView terminal to
acknowledge that a multiplex module data exchange has taken place.
The DP Master’s program is responsible for checking the Block In
and Block Out values to determine if the exchange took place
successfully.