Rockwell Automation 2711 PanelView 550/900 Profibus Communications User Guide - Manual (Page 19)

PROFIBUS DP Communications 19
Publication 2711-6.3
Handshaking Flow Chart
Multiplex Inputs and Outputs are available to the DP Master by
management of the handshake words. Use the following flow chart
to assist in creating and implementing the control program.
Start
Set Command Word
Handshake Bit to 0
Load Block Output
and Block Input Fields of the
Command Word
Load Multiplex
Output Data From DP
Master Database
Set Command Word
Handshake Bit to 1
A
Is Status Word
Handshake Bit
Set to 1?
Block Output and
Block Input Fields of Status
Word Available to Identify Data
Input Fields
Read Multiplex Input
Data Fields and Store in DP
Master Database
Is Status Word
Handshake Bit
Set to 0?
A
Write from application
program. Can occur
concurrently.
Read from application
program. Can occur
concurrently.
NO
YES
YES
NO