Chapter 4: System Operation; System Overview; Communications; Redundancy - Emerson PACSystems RX3i User Manual

User Manual
GFK-2949E

Chapter 4: System Operation

This chapter provides a System Overview and describes:
•

Communications

•

Redundancy

• I/O Scans
• Alarms
• Station Manager
4.1

System Overview

4.1.1 Communications
The EIS001 is a self-standing communication processor. During normal operation, it handles
asynchronous requests from its IEC 104 Client and exchanges corresponding data with the
host RX3i CPU at designated portions of the CPU scan. It performs all these tasks without
burdening the CPU beyond the windows designated for data exchange.
On power-up or reset it will await the COMMREQ from the user application environment to
set parameters and put it into operation. Once it receives the parameters, the module scans
the RX3i for data, based on its configuration. It detects and registers data changes within its
host Controller. It also services asynchronous IEC 104 Client requests for polling (such as
reading of Controller data) and writing of data to Controller memory.
Because the module is self-standing, it polls the CPU during the CPU background scan
window for data, per its configuration. The module detects and records all corresponding
data changes internally. Whenever a Client writes to it, the module must wait for the CPU to
allow it to write the corresponding information into the Controller memory during the same
window.
All Ethernet traffic is asynchronous to the RX3i CPU scanning operation, so the module can
service many different requests without burdening the CPU with processing them.
4.1.2 Redundancy
There are no restrictions that apply to an EIS001 when installed in a redundant RX3i CPU.
The polling of event and integrity data will occur as if it were in a simplex system.
The EIS001 can take advantage of the Redundant IP feature of a Redundant CPU system,
allowing two EIS001 modules in two racks to appear as one module.
System Operation
Chapter 4
Dec 2020
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