Rockwell Automation 1794-OF8IH FLEX Isolated Input/Output HART Analog Modules - Manual (Page 39)

Publication 1794-UM065B-EN-E - September 2010
Input, Output and Configuration of the FLEX I/O HART Analog I/O Modules 27
Configuration data is not continuously updated to the module.
Scheduled Data Transfer
Scheduled data transfer:
• is continuous.
• is asynchronous to the controller program scan.
• occurs at the actual rate displayed in the Actual Packet Interval field on
the programming software ControlNet I/O mapping (monitor) screen.
Unscheduled Data Transfer
Unscheduled operations include:
• unscheduled nondiscrete I/O data transfers – through ControlNet I/O
Transfer (CIO) instructions.
• peer-to-peer messaging–through message (MSG) instructions.
• messaging from programming devices.
Unscheduled messaging on a network is nondeterministic. Your application
and your configuration (for example, number of nodes, application program,
NUT, and amount of scheduled bandwidth used), determine how much time
there is for unscheduled messaging.
Module I/O Mapping
The I/O map for a module is divided into read words and write words. Read
words consist of input and status words, and write words consist of output and
I/O Module I/O Module I/O Module
Configuration Configuration Configuration
Inputs Inputs Inputs
Status
Outputs
Status Status
Outputs Outputs
Read
Words
Write
Words
0
X
Slot 0 Slot 1 Slot 7
Network
Network
Adapter
Read
Write