Omron CJ1W-PNT21 Operation Manual page 38

Setting up the PROFINET IO network
3-4-3 PROFINET IO Controller redundancy
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The network requires an MRP manager to facilitate the redundancy. As an
MRP client, there are no specific settings required for the Omron GRT1-PNT
IO Device Unit. Please refer to the manual of the used MRP manager unit for
details on how to set up and operate the MRP network.
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In case a connection fails, MRP Ring Redundancy ensures communication to
all devices through the alternative path.
The PROFINET IO Controller redundancy feature ensures a seamless
change-over of the active PLC / IO Controller to the standby PLC / IO
Controller in case of malfunction. To support redundancy for the PROFINET
IO Controller a redundancy Function Block can be downloaded from the
OMRON website.
Both the active and the standby IO Controller exchange data with all IO
Devices in the network. However, only the active IO Controller is in control of
the outputs of the IO Devices.
The I/O data sent from the IO Controller to the I/O Device and vice versa
includes data state information. This data-state information is used to signal to
the receiving side that the I/O Data is valid or invalid. In case of invalid the
receiving side will discard the data.
For IO Controller redundancy, the PROFINET IO Device must be capable of
handling relations to multiple IO Controllers. It is up to the IO Device to handle
the situation where both IO Controllers signal that the output data is valid.
Normally the first IO Controller that signalled that the output data is valid will
be in control of the outputs of the IO Device. OMRON can therefore only
guarantee proper IO Controller redundancy operation if implemented with
GRT1-PNT IO Devices.
In case of malfunction of the active IO Controller the Function Block will
transfer control to the standby PLC system. To avoid momentary changes in
output data during this control change the Data Hold parameter of each IO
Device should be set sufficiently high for the standby IO Controller to take over
seamlessly. The appropriate Data Hold value should be determined
experimentally.
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MRP ring redundancy
Figure 3.11:
Section 3-4
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