Honeywell HC900 User And Installation Manual page 26

Introduction

Redundant CPUs - Redundancy is provided by two C75 CPUs operating in a controller rack; this rack has no
I/O. A Redundancy switch module (RSM) sits between the CPUs.

Redundant CPU Power - Two power supplies, P01 and P02 one for each C75 CPU. Model numbers are 900P01-
0101, 900P01-0201, 900P02-0101, 900P02-0201

Redundant CPU-I/O connection – Each CPU has its own 100 base-T Ethernet physical communication link with
one or more racks of I/O. Multiple I/O racks require Ethernet switches.

I/O racks – 5 racks shown, top to bottom: 4-slot w/1 power supply, 8-slot w/1 power supply, 12-slot w/1 power
supply, 8-slot w/redundant power supplies, 12-slot w/redundant power supplies. A Power Status Module (PSM) is
required with redundant power supplies. High and low capacity power supplies are available.

Dual Networks for Host communications - Dual Networks for Host communications are provided on the C75 CPU.
Both network ports are continuously active on the Lead controller. The network ports on the Reserve CPU are not
available for external communications. Experion HS and the 900 Control Station (15 inch model) support Dual
Ethernet communications and automatically transfer communications to the opposite E1/E2 port during a network
failure. Connections to these ports are to be considered part of the control network layer and as such care must be
taken to reduce exposure to uncontrolled/ unknown network communications. A properly configured firewall such as
the MOXA EDR-810 is recommended to help mitigate the exposure.

Scanner 2 module – has 2 ports, one for each CPU connection to I/O. This IO network between the controllers
and scanners is considered proprietary with no other Ethernet traffic.
12 HC900 Process & Safety Controller User and Installation Manual Revision 6
21 April 2017