Rockwell Automation 1794-L34 FlexLogix Controller System User Manual - Manual (Page 63)

Publication 1794-UM001G-EN-P - January 2007
Place, Configure, and Monitor I/O 63
Determine When Data
Is Updated FlexLogix controllers update date asynchronous with the execution of
logic. Use the following flowchart to determine when a producer
(controller, input module, or bridge module) will send data.
For more information... See Logix5000 Controllers Common Procedures Programming
Manual, publication number 1756-PM001 for examples of I/O
buffering or to the Logix5000 Controllers General Instruction Set
Reference Manual, publication number 1756-RM003 for information
on the CPS instruction.
input or output data?
input
output
COS for any point on the
module?
Data is sent to the backplane at the
RPI
remote or local?
analog
No
Yes
Data is sent to the backplane at the RPI
and at the end of every task.
Data is sent to the backplane at the RPI
and at the change of a specified point.
Data is sent to the backplane at
the RTS and RPI. Data is sent to the backplane
at the RTS.
analog or digital?
analog
digital
local
remote
digital
• Over a ControlNet network, remote data is sent at the actual packet interval.
• Over an EtherNet/IP network, remote data is sent close to the RPI, on average.
Yes
No
RTS
≤ RPI?
analog or digital?
TIP
If you need to ensure that the I/O values being used during logic
execution are from one moment in time (such as at the
beginning of a ladder program), use the Synchronous Copy
instruction (CPS) to buffer I/O data.