PACSystems RX3i Manual

GFK-2511H
July 2013
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The PACSystems Redundancy Memory Xchange (RMX) module
operates as a node on a reflective memory network or as a dedicated
link between CPUs in an RX3i Hot Standby CPU Redundancy system.
When the RMX is not being used as a link in a redundancy system, it
is functionally identical to the IC695CMX128 module. Each node in the
network can be any reflective memory device that is compatible with
the 5565 family. Whenever data is written to one node, all nodes on
the network are automatically updated with the new data.
When used as a node on a reflective memory network, the RMX
module provides deterministic sharing of data among PLCs and other
computing devices on a high-speed fiber optic network. A reflective
memory network can contain up to 256 nodes.
Each node in the reflective memory network is connected in a daisy-
chained loop using fiber optic cables. The transmitter of the first node
is tied to the receiver of the second. The transmitter of the second
node is tied to the receiver of the third node, and so on, until the loop is
completed at the receiver of the first node.
When used in a CPU redundancy system, the RMX modules provide a
path for transferring data between the two redundancy CPUs in the
redundant system. A complete communications path consists of one
RMX in the primary unit, one RMX in the secondary unit, and two high-
speed fiber optic cables connecting them to each other. This must be a
two-node ring: no other reflective memory nodes are allowed to be part
of this fiber optic network.
GE Intelligent Platforms strongly recommends two redundancy links
(a total of four RMX modules) be configured and installed. Optionally,
systems can be configured for a single redundancy link (a total of two
RMX modules).
When the RMX is being used as link in a redundancy system, it cannot
be used as a general-purpose Memory Xchange module. For details
on the operation of a PACSystems CPU redundancy system, refer to
the PACSystems Hot Standby CPU Redundancy User's Manual,
GFK-2308.
A PACSystems RX3i main rack supports a maximum of six Memory
Xchange modules in any combination of RMX128 and CMX128
modules. A maximum of two RMX modules can be configured as
redundancy communication links.
*
indicates a trademark of GE Intelligent Platforms, Inc. and/or its affiliates. All other trademarks are the property of their
respective owners. All rights reserved.
PACSystems* RX3i
Redundancy Memory Xchange Module
IC695RMX128-CG