I/O Scanning - GE PACSystems RXi User Manual

Chapter 10. PROFINET IO-Controller Operation

I/O Scanning

10.3
In the PACSystems RXi PROFINET network, multiple I/O cycles run asynchronously and
independently. The example below illustrates typical cycles in a system with an RXi
Controller and VersaMax PNS modules used as IO-Devices. Cycles may be different for
other GE Intelligent Platforms scanners and third-party devices.
208
PROFINET IO
Production Cycle
P
P
N
S
S

PROFINET IO-Device
modules in its node as quickly as possible. The PNS stores the modules' input data
into its internal memory. On each PNS output scan, the Scanner writes the output
data from its internal memory to the modules in its node.

PROFINET IO Production
from its internal memory onto the network at each scheduled PROFINET production
cycle. The PNC publishes output data received from the RXi CPU to each IO-Device,
and the IO-Device publishes input data from its memory to the PNC.
Note: Production cycles between IO-Controllers and IO-Devices are not
synchronized, each publishes at its configured update rate independently.

RXi CPU Sweep: the sweep includes both an input scan and an output scan. The
CPU input scan retrieves the current input data from the PNC. This input data is then
available for use by the application logic. After the logic solution, the CPU output
scan writes the outputs to the PNC.

3rd party devices: The conveyance of I/O data between an I/O module and the
PROFINET IO network is device dependent. Third party manufacturer documentation
should be referred to for specifics for a particular device.
PACSystems* RXi Distributed IO Controller User Manual
C P
P N
U C
PROFINET IO
P
P
DI N
S
S
Scan: in this example, each VersaMax PNS scans all the
Cycle: each PNC and each IO-Device publishes data
RXi CPU Sweep
PROFINET
IO-Device Scan
DI
GFK-2816F