Description
Honeywell 51303979-400
Technical Specifications
- Host Side Interface: DCS proprietary backplane bus
- External Serial Interface: Configurable RS232 and RS485
- Isolation Rating: 500 VAC reinforced isolation
- Operating Temperature: -10 °C to +65 °C
- Supply Power: 5 VDC and 24 VDC from rack backplane
- Baud Rate Range: 300 bps to 38400 bps
- Form Factor: Plug-in DCS rack card
Functional Features Bidirectional protocol conversion between internal DCS bus and external serial devices. Enhanced transient surge protection circuit for field serial wiring. Checksum validation on all inbound and outbound communication frames. Serial bus timeout, parity and framing error diagnosis. Front panel TX, RX and fault LED indication. Larger onboard message buffer supports higher baud rate continuous transmission. Backward compatible with existing 51303979-100H rack configuration.
Application Scenarios Outdoor located serial analyzer connection to DCS system Long distance RS485 field device communication interface Legacy Honeywell DCS serial gateway upgrade and replacement Petrochemical plant process serial data interconnection
Performance Parameters
- Serial baud rate range: 300 bps up to 38400 bps configurable
- Message forwarding latency: Deterministic within DCS scan cycle
- Fault detection response: <200 ms
- Isolation withstand voltage: 500 VAC for 60 seconds
Material Composition FR4 multilayer PCB, upgraded serial transceiver IC, protocol processing FPGA, high grade optocoupler isolation components, high power TVS surge suppression diodes, screw terminal block for RS485 wiring, DB9 connector for RS232, flame retardant plastic housing, gold plated backplane edge connector.
Structural Features Standard plug-in rack card form factor. Front panel LED indicators for transmit, receive and fault state. External serial connectors arranged on front panel for field wiring access. Internal isolation barrier separates rack logic circuit and external serial circuit. Anti-keying notch prevents reversed insertion.
Working Principle DCS controller sends read or write request over rack backplane bus. Onboard FPGA repackages request into serial protocol frame and transmits to external device. Response frame received from serial port is validated by checksum, parsed and converted back to DCS bus message format before sending to controller. Continuous bus monitoring detects timeout and framing error. The upgraded surge circuit suppresses larger transient voltage spikes on field cables.
Installation Requirements RS485 field wiring uses twisted pair differential cable and install termination resistor at bus far end. Separate serial communication cable from high voltage power wiring. Configure baud rate, parity and protocol mode to match connected third-party device. Tighten terminal screws to specified torque value. Verify rack firmware compatibility before replacement.
Usage Notes Do not swap A and B differential lines on RS485 bus. Duplicate termination resistors cause communication failure. External surge protection can be added for extremely long field cable runs. Do not modify onboard protocol firmware without factory release package.
