Honeywell TK-PRS021 Control Processor C200 (51404305-375) Product Introduction
Product Overview
The Honeywell TK-PRS021 is a control processor module for process automation control systems, belonging to the C200 controller family. Part number 51404305-375 corresponds to its PCB material code. This module is the core unit responsible for real-time control calculation, logic execution, I/O scheduling, alarm processing, and data interaction between the controller and the system network. It is widely deployed in continuous process industrial sites.
The TK-PRS021 mounts into the Series A rack and occupies 2 slots for a single unit. For redundant configuration, it can work with the TK-PRR021 redundancy synchronization module to achieve 1:1 hot standby of the controller. When the primary controller fails, the backup controller automatically takes over control tasks to minimize production downtime.
As a core CPU unit of Honeywell early DCS controller platform, this product has been discontinued. Available supplies on the market are spare parts, refurbished units or used stock.
Hardware Specifications
| Item | Parameter |
|---|---|
| Model | TK-PRS021 |
| Part Number | 51404305-375 |
| Product Type | Control Processor |
| Compatible Controller | C200 |
| Rack Type | Series A |
| Slot Occupancy | 2 slots |
| Processor | 100MHz processor |
| User Memory | 4MB |
| Power Supply | Powered by Series A rack backplane |
| On-board Power | +5VDC, +3.3VDC |
| Power-off Data Retention | Built-in backup battery for retaining programs, variables and data after power loss |
| Battery Hold Time | Up to approximately 144 hours |
| Surface Protection | Conformal coating to resist humid and corrosive industrial environments |
| Operating Temperature | -20℃ ~ +60℃ |
| Storage Temperature | -40℃ ~ +70℃ |
| Relative Humidity | 5% ~ 95%RH, non-condensing |
| Explosion-proof Rating | Class I Div.2, Groups A, B, C, D, T4A |
| Certifications | UL, CE, CSA |
| Weight | Approx. 0.5kg |
Key Features
Real-time Control Processing
The TK-PRS021 acts as the computing core of the C200 controller. It executes control strategies, continuous loop control, logic operations, timing/counting, data calculation, alarm detection and sequence of events recording. The module schedules control programs in fixed cycles, ideal for process control applications requiring high response speed and stability.
Redundant Control Support
In redundant setup, TK-PRS021 works alongside TK-PRR021. The primary and backup controllers synchronize programs, variables and status continuously. Upon primary controller failure, the system switches to the backup controller automatically to maintain uninterrupted process operation.
I/O Network Management
TK-PRS021 has no direct field I/O terminals. It connects to the I/O subsystem via the controller network to manage analog input, analog output, digital input and digital output modules, collecting field signals and transmitting control commands.
System Communication
The controller links to the I/O subsystem through the control network, and exchanges process variables, alarms, trend data and operator commands with servers and operator stations over the upper industrial network.
Self-diagnosis & Status Indication
The module supports hardware self-check, battery status monitoring, communication link diagnosis and fault localization. Front panel LEDs indicate power, run, fault and redundancy status to help maintenance personnel quickly troubleshoot on-site issues.
Power-off Data Protection
The built-in backup battery preserves control programs, parameters and real-time variables during external power interruption. If the battery fails and power remains off for an extended period, control programs may need re-downloading after power restoration.
Position in System Architecture
The TK-PRS021 sits at the field control layer of the DCS architecture. It connects upward to system servers and operator stations, and downward to the I/O subsystem and field devices.
Typical structure: Operator Station / Server → Controller Network → C200 Controller (TK-PRS021) → I/O Subsystem → Field Sensors / Actuators
Operation Modes
- Simplex Controller Configuration: A single TK-PRS021 runs independently, suitable for non-critical loops or applications with relatively simple control requirements.
- Redundant Controller Configuration: Dual primary/backup controllers paired with TK-PRR021. Designed for continuous production plants with high downtime costs.
Typical Applications
TK-PRS021 serves as the control unit for process industries, including:
- Oil Refining
- Oil & Gas
- Chemical Industry
- Power Generation
- Water Treatment
- Pharmaceutical
- Paper & Pulp
- Metallurgy
It controls temperature, pressure, flow, level, composition and other process parameters, supporting single-loop control, complex interlocks, sequence control and batch process monitoring.
Appearance & Identification
TK-PRS021 is a standard rack-mount industrial module with a black plastic housing. The front face is fitted with status LED indicators and a yellow warning label. A white nameplate label is usually attached to the side, marking model number, part number, revision, firmware version, origin and certification marks. The module plugs into the Series A rack via backplane connectors for power supply and internal communication.
Spare Parts & Replacement Guide
This product is discontinued, and brand-new units are not available. Market supplies mainly consist of spare parts, refurbished assemblies and used pulled units. When sourcing, verify model number, part number, hardware revision, firmware status and test reports.
For system upgrade projects, C200 controllers can be migrated to newer controller platforms. Some existing I/O modules and control strategies can be retained during migration to reduce transformation risks and costs.
Frequently Asked Questions
Q1: Does TK-PRS021 come with built-in I/O interfaces?
A: No. It is a control processor module for control calculation and network scheduling. I/O functions are implemented by separate I/O modules.
Q2: Is TK-PRR021 mandatory for redundant control?
A: Yes. TK-PRR021 handles status synchronization and failover management between redundant controller pairs.
Q3: What happens if the backup battery fails?
A: If the battery is defective and power loss lasts for a long time, programs, parameters and real-time variables may be lost. You will need to re-download control programs after power recovery.
Q4: What is the difference between TK-PRS021 and TC-PRS021?
A: They belong to similar controller modules. Differences lie in PCB version, production batch and minor hardware details. Always follow your system configuration and spare parts list for replacement.
