Rockwell Automation 2711 PanelView 550/900 Profibus Communications User Guide - Manual (Page 17)

PROFIBUS DP Communications 17
Publication 2711-6.3
Multiplex Module Handshaking
It is the DP Master’s role to manage the handshake operation. This
is accomplished by initiating an exchange using the multiplex output
module’s control word and monitoring progress of the exchange in
the multiplex input module’s status word. The timing diagram
below shows the operation of the Handshake Bit controlled by the
DP Master and the one controlled by the PanelView terminal.
PanelView
Input Handshake Bit
DP Master
Output Handshake Bit
DP Master sends/requests new data
PanelView acknowledges reception of data / sends requested data
DP Master resets handshake bit
PanelView ready to process new data / request
Time
Command Word / Handshake Bit
Status Word / Handshake Bit