Honeywell 51309355-001 Processor Board

The Honeywell 51309355-001, also cataloged as the 51309355-001 Processor Board, operates as a dedicated hardware component for executing real-time algorithm calculations and control processing within Honeywell DR4500 Classic Circular Chart Recorder systems.

Hardware Specifications

Process Control & Loop Performance Integration

The 51309355-001 microprocessing engine serves as the main computational board inside the circular chart recorder, directly orchestrating the acquisition, digitization, and charting of field process variables.

• 4-20 mA HART Loop Integration: The processor board coordinates the incoming digitized signals from 4-20 mA transmitter loops, RTD, and thermocouple inputs, executing local mathematical scaling and routing the formatted values to the display and servo pen-drive assemblies.
• A/D Conversion and Multi-Channel Isolation: It supports multi-channel processing with high common-mode noise rejection, ensuring that industrial electromagnetic interference does not compromise loop calculation accuracy.
• Cold Junction Compensation (CJC): The board interfaces directly with local input terminal assemblies containing temperature-sensitive reference resistors to perform real-time cold junction compensation for all standard thermocouple curves (Type J, K, T, E, R, S, B).

Frequently Asked Questions

• Q: Does the 51309355-001 processor board support hot-swapping while the DR4500 recorder is active?
• A: No. All power to the DR4500 circular chart recorder must be completely isolated before extracting or inserting the processor board. Attempting to replace the board under load will cause severe voltage transients that can permanently corrupt the socketed firmware EPROMs or destroy downstream driver circuitry.
• Q: What is the purpose of the onboard lithium coin-cell battery?
• A: The onboard battery preserves system configuration variables, calibration factors, and time-stamped history logs within the volatile SRAM during periods of primary instrument power loss.
• Q: How are firmware upgrades or program modifications managed on this board?
• A: The firmware is programmed onto physical, socketed Dual In-line Package (DIP) EPROM chips. Modifying the system operating program requires replacing these physical chips with verified, updated hardware versions.

Field Installation Guidelines

• Electrostatic Protection Mandate: This board houses highly sensitive complementary metal-oxide-semiconductor (CMOS) microchips. Technicians must wear a grounded ESD wrist strap and handle the PCB only by its non-conductive fiberglass borders to prevent static damage during installation.
• Chassis Ground and Shield Termination: Ensure the recorder enclosure has a low-impedance connection to a dedicated protective earth (PE) ground. Signal cable shields from 4-20 mA transmitters or thermocouples must be grounded according to the system layout instructions to prevent ground loop currents.
• Ribbon Cable Connection Integrity: Carefully align and firmly press home the multi-pin ribbon cables extending from the power supply, display, and pen drive assemblies to the corresponding headers on the 51309355-001 board. Ensure the locking tabs are fully clicked to prevent contact resistance caused by industrial physical vibrations.