Omron PROFINET NX-PNC202, User Manual

Page: 188 / 282

10 I/O Refreshing
10 - 2
NX-series PROFINET Coupler Unit User’s Manual (W623)
10-1 Introduction to I/O Refreshing for
PROFINET IO Devices
This section introduces I/O refreshing for NX-series PROFINET IO Devices.
The PROFINET IO Controllers perform I/O refreshing cyclically with the NX Units in a PROFINET IO
Device through PROFINET communications and the NX bus. The following four cycles affect the oper-
ation of I/O refreshing between the PROFINET IO Controllers and the NX Units in a PROFINET IO
Device.
(A) Cycle Time in the PROFINET IO Controllers
(B) PROFINET communication period
(C) Refresh Cycle of the NX bus = 16 ms
(D) Refresh Cycle of each NX Unit
I/O refreshing operates asynchronously between the PROFINET IO Controllers and IO Devices.
The following figure shows the operation of I/O refreshing with a PROFINET IO Device.
NX Unit
(A) PLC cycle time
PROFINET port
I/O refreshing between the CPU
Unit and NX Units
Communications path
Other PROFINET IO Devices
(D) Refresh cycle of
each NX Unit
(C) Refresh cycle of the NX bus
PROFINET
Coupler Unit
PROFINET IO Devices
NX Unit NX Unit
PROFINET IO Controller