HONEYWELL ControlEdge HC900 900RR0-0101 Redundant CPM Rack Original new

The Honeywell 900RR0-0101 is a dedicated redundant CPU rack assembly purpose‑built for the ControlEdge HC900 platform. This Honeywell 900RR0-0101 houses two C75 CPUs in a hot‑backup configuration, providing fault‑tolerant architecture for safety‑critical and high‑availability processes. The Honeywell 900RR0-0101 eliminates single points of failure at the controller level by orchestrating seamless automatic switchover between the primary and standby units. Designed as a dedicated controller rack with no I/O slots, the 900RR0-0101 supports dual redundant power supplies and works in conjunction with the Redundancy Switch Module (RSM) to ensure bumpless transfer during failover events.

Oil & Gas Refining: Maintains continuous process control during CPU maintenance or unplanned failures

Chemical Processing: Guarantees uninterrupted safety instrumented functions (SIF) in SIL‑rated environments

Power Generation: Provides bumpless transfer between redundant controllers in turbine control, boiler management, and critical power station systems

Pharmaceutical Manufacturing: Prevents production stoppages during firmware upgrades or hardware replacement

Water/Wastewater Treatment: Enables high‑availability control for critical pumping, filtration, and distribution operations

Pipeline Monitoring: Sustains 24/7 supervisory control and data acquisition (SCADA) across remote assets

Metal & Mining: Delivers fault‑tolerant logic for material handling, conveyor systems, and processing equipment

Safety Instrumented Systems (SIS): Provides the physical backbone for dual‑CPU failover control in safety‑critical loops

Dual CPU Redundancy: Designed to house two C75 CPUs operating in a hot‑backup 1:1 redundant configuration, ensuring seamless failover with automatic bumpless transfer

Dedicated Controller Rack: The rack contains no I/O slots – all I/O is housed in separate expansion racks, isolating the control function from field I/O

Dual Redundant Power Supply Support: Each CPU receives its own independent power supply (P01 and P02), eliminating a single point of power failure

High‑Integrity Backplane: Provides deterministic communication and power distribution between redundant CPUs and the Redundancy Switch Module

RSM Integration Ready: Includes dedicated slot and backplane connections for the Redundancy Switch Module (900RSM-0101) positioned between the CPUs

Private I/O Network Architecture: Each C75 CPU has its own dedicated 100 Base‑T Ethernet physical link to I/O racks, ensuring redundant communication paths

Passive Cooling Design: Fanless convection cooling eliminates moving parts, reducing maintenance and improving long‑term reliability

Robust Industrial Construction: Heavy‑gauge steel chassis with built‑in grounding bars provides EMI protection and mechanical durability for harsh environments

Compliance Standards: Certified to IEC 60664 and UL 840 installation standards, with ATEX and cULus options for hazardous locations

Seamless ControlEdge HC900 Integration: Pre‑engineered and tested for optimal performance within Honeywell’s high‑availability control ecosystem

Physical Housing for Redundant CPUs: Provides the mechanical and electrical infrastructure to host a pair of C75 processors in a dedicated controller rack, including backplane connectivity, power distribution, and grounding

Automatic Failover Orchestration: Monitors the health of both the lead and reserve CPUs and automatically transfers control to the standby unit upon detection of a fault, enabling sub‑second bumpless transfer transparent to the process

Redundant Power Distribution: Physically accommodates and distributes power from two independent power supplies, one dedicated to each C75 CPU, ensuring continuous operation even if one supply fails

CPU State Synchronization: Supports inter‑CPU communication via dedicated backplane links for real‑time memory mirroring and process data synchronization between lead and reserve controllers

Private I/O Network Backplane: Provides the physical interface for each C75 CPU to connect (via external Ethernet switches) to Scanner 2 modules in I/O racks, with each CPU maintaining its own dedicated communication link

RSM Integration and Interface: Includes the physical slot and backplane connections required for the Redundancy Switch Module to sit between the CPUs and manage mode control and failover decision logic

Grounding and Noise Immunity: Incorporates built‑in grounding bars for field wiring shields and protective earth connections, essential for proper electrical noise rejection in safety applications

Q1: What is the purpose of the Honeywell 900RR0-0101?
A1: The Honeywell 900RR0-0101 is a dedicated redundant CPU rack that provides the physical and electrical infrastructure to host two C75 CPUs in a hot‑backup configuration. It works with the Redundancy Switch Module (900RSM-0101) and dual power supplies (900P01/900P02) to create a fault‑tolerant controller system that can fail over automatically without process interruption. This dedicated controller rack contains no I/O slots.

Q2: Does the 900RR0-0101 have its own I/O slots?
A2: No. The 900RR0-0101 is a dedicated controller rack that has NO I/O slots. All I/O modules must be housed in separate expansion racks (4‑slot, 8‑slot, or 12‑slot) connected to the controller rack via private Ethernet links through Scanner 2 modules. This architecture isolates the redundant control function from field I/O.

Q3: What components are required to build a complete redundant controller system around the 900RR0-0101?
A3: A complete redundant controller system requires: two C75 CPUs, two independent power supplies (900P01 or 900P02), one Redundancy Switch Module (900RSM-0101), and the Honeywell 900RR0-0101 rack assembly. Each CPU requires its own I/O network link to Scanner 2 modules. For power redundancy, a Power Status Module (PSM) is required when using a second power supply in I/O racks. All component model numbers must match for compatibility.

Q4: What happens when a failover occurs in the 900RR0-0101 rack?
A4: When the lead CPU fails, the backup CPU assumes control immediately. The Redundancy Switch Module within the 900RR0-0101 rack detects the fault and executes an automatic sub‑second, bumpless transfer to the standby controller. The new lead CPU continues to communicate with I/O racks over its dedicated Ethernet ports, and the reserve CPU (previously the failed unit) is automatically synchronized once repaired or replaced.

Q5: Is the 900RR0-0101 suitable for safety instrumented systems (SIS)?
A5: Yes. The 900RR0-0101 is designed for safety‑critical applications requiring dual CPU failover control. It meets IEC 60664 and UL 840 installation standards and can be configured for ATEX and cULus hazardous locations. For full SIL compliance, the Safety Controller CPU modules (900C75S) must be used, the physical mode switch on the RSM must be placed in the RUN‑LOCKED position, and the entire system must be installed in a grounded metal enclosure with a properly configured firewall (e.g., MOXA EDR‑810) for network security.