Chapter 1
.
Introduction
Media Redundancy Protocol Support
PROFINET Media Redundancy Protocol (MRP) supports devices configured in a ring topology.
MRP is specified as part of IEC62439 and has been adopted by the PROFINET specification,
which provides for convenient configuration of the ring topology and necessary parameters.
Like PROFINET IO data, Media Redundancy Protocol operations are not routable between
different IP subnets.
Each device within an MRP ring has two physical pathways to the IO-Controller. To connect to
the ring, each device requires an integrated switch with at least two external ports (ring ports)
that support MRP. Devices that are not MRP-capable can be connected to a device in the ring
(i.e., an MRP-capable switch in the ring), but they should not be in the ring themselves. The
redundancy capability offered by the ring topology only extends to the devices on the ring
that are MRP-capable and enabled.
One of the devices on the ring must be configured as the Media Redundancy Manager (MRM),
and all the other devices must be configured as Media Redundancy Clients (MRCs). The
GCG001 can be configured as an MRC. Configuring the GCG as an MRC alters how the
Ethernet ports connect to the network. They attempt to indicate their state to the MRM before
allowing traffic to flow between the ports and close the ring topology through the internal
switch. They also send out notifications to the MRM when a port is lost. Operation of the
GCG001 is otherwise unchanged.
The MRP configuration is stored in non-volatile storage in the GCG001 and activated
immediately upon powering up. Non-volatile storage is updated as part of a connection with
the IO-Controller. A PROFINET Discovery & Configuration Protocol (DCP) Reset disables MRP
Client operation and updates non-volatile storage. The current state of the MRP configuration
is provided as part of the GCG’s Gateway Status Bits which are accessible to user application
logic. Refer to the description of Gateway Status Bits in Section 5.1.1 for further details.
Fast ring-break detection is not fully functional until all MRP clients have received their MRP
configuration. For a discussion of ring-break detection, refer to the following section,
Bumpless Operation with MRP
The GCG001 supports bumpless operation under MRP.
1.6
System Limits
IO-Controllers have limitations on the size of the system they support. One of these limits is
the number of PROFINET sub-modules supported. The GCG001 uses four sub-modules: two
for basic operation and two built-in port sub-modules that are always configured. Each
Genius device attached to a GCG001 uses one additional sub-module.
Other limitations, such as the configuration and IO sizes are specific to the configuration
options chosen. Note that not every combination of options is supported in every system. If
the configuration uses all Genius bus slots with a corresponding large device count, the
memory of the IO-Controller system will be a limiting resource.
See GFK-2571 for actual limits in the RX3i PROFINET Controller (PNC001).
See GEK-90486,
Genius I/O System and Communications User's Manual
for information on how
much I/O, and which type of I/O, need to be allocated to Genius devices,
Machine Edition (v8.0 or later) takes into account both system limits and I/O allocation.
GFK-2892B
PACSystems RX3i Genius Communications Gateway User Manual
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