Comprehensive Product Summary – RAYON P485U 4-Port RS422/485 PCI Board (incl. Cable A404)

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### 1. Product Overview

Product Name: UPCI 4-Port RS422/485 Board
Model: P485U
Series: RAYON PCIPORT Universal PCI Serial Communication Series
Article Number: P485U
Manufacturer: Rayon Technology Inc.
Included Cable: A404 (DB37 female to 4 × DB9 male)

The RAYON P485U is a universal PCI (UPCI) intelligent 4-port serial communication board designed for industrial and embedded PC systems requiring reliable multi-port RS422/RS485 connectivity. It supports both 3.3V and 5V PCI slots at 33MHz and provides four independent, DIP-switch-selectable RS422 or RS485 serial ports. Each port is 16550A UART compatible, supporting data rates from 50 bps up to 115.2 kbps (standard) or up to 921.6 kbps with an optional higher-frequency crystal. The board is based on the Broadcom (PLX) PCI9030 controller and is fully Plug & Play compliant, with automatic resource allocation by the PCI BIOS.

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### 2. Key Features

- Four Independent Serial Ports:
Each port can be configured individually for RS422 or RS485 operation via DIP switches.

- Universal PCI Compatibility:
Supports both 3.3V and 5V PCI slots, ensuring compatibility with a wide range of modern and legacy systems.

- High Performance UARTs:
Each port uses a 16550A-compatible UART with 16-byte transmit and receive FIFOs, reducing CPU overhead and improving throughput.

- Automatic Data Direction Control (ADDC):
Built-in ADDC circuitry for RS485 mode automatically manages data direction, eliminating the need for software RTS control.

- Plug & Play Configuration:
IRQ and I/O address mapping are automatically assigned by the PCI BIOS. The card supports IRQ sharing across multiple PCI devices.

- Flexible Baud Rate Support:
Software-programmable baud rates from 50 to 115,200 bps (standard 1.8432 MHz crystal) or up to 921,600 bps (optional 14.7456 MHz crystal).

- Multi-OS Driver Support:
Compatible with DOS, Windows 95/98/ME/NT/2000/XP, Linux, and SCO OpenServer.

- Compact Form Factor:
PCB dimensions of 122 mm × 101 mm, suitable for standard PCI slots.

- Industrial-Grade Design:
Designed for robust operation in industrial environments, with optional termination resistors and isolated ground per port.

- Included Cable Assembly:
Ships with A404 cable (DB37 female to 4 × DB9 male connectors). Optional A400 cable (DB37 to 4 × DB25 male) available on request.

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### 3. Technical Specifications

Electrical & Interface:
- PCI Bus: 32-bit, 33 MHz, 3.3V/5V Universal PCI
- Controller: Broadcom (PLX) PCI9030 ASIC
- UART: 16550A compatible with 16-byte FIFO
- Ports: 4 × RS422/RS485 (DIP-switch selectable)
- Baud Rate: 50 bps to 115.2 kbps (standard), up to 921.6 kbps (optional)
- Flow Control: Hardware (RTS/CTS) and Software (XON/XOFF)
- IRQ: Shared, assigned by PCI BIOS
- I/O Mapping: Assigned by PCI BIOS (Plug & Play)

Physical Characteristics:
- Dimensions: 122 mm (L) × 101 mm (W)
- Weight: Approx. 120 g (board only)
- Connector: DB37 female on board
- Cable: A404 (DB37F to 4 × DB9M)
- Material: Multi-layer PCB, industrial-grade components

Environmental:
- Operating Environment: PC/AT compatible systems with PCI bus
- Power Requirements: 3.3V or 5V PCI slot power
- Operating Temperature: 0°C to 55°C (typical)
- Storage Temperature: -20°C to 85°C
- Humidity: 5%–95% non-condensing

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### 4. Functionality

The P485U functions as a four-port serial communication controller card for PCs with PCI expansion slots. Each port can operate in either RS422 (full-duplex) or RS485 (half-duplex) mode, selectable via DIP switches.

RS422 Mode:
Used for point-to-point or multi-drop full-duplex communication. Each port provides differential transmit (TXD+/TXD−) and receive (RXD+/RXD−) pairs for noise-immune data transmission over long distances.

RS485 Mode:
Used for multi-drop half-duplex networks. The card’s Auto Data Direction Control (ADDC) automatically manages the transmit/receive switching, simplifying software implementation.

Use Cases & Applications:
- Industrial automation and control systems
- Data acquisition and instrumentation
- Building management systems
- SCADA and telemetry networks
- Serial device networking (PLC, sensors, HMIs)
- Multi-drop RS485 communication buses

Compatibility:
- Operating Systems: DOS, Windows 95/98/ME/NT/2000/XP, Linux, SCO OpenServer
- Hardware: Compatible with standard PCI 2.1-compliant motherboards
- Software: Supports standard COM port addressing and driver models

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### 5. Components & Accessories

Included in Package:
- 1 × P485U PCI interface card
- 1 × A404 cable (DB37 female to 4 × DB9 male connectors)
- 1 × User manual

Optional Accessories:
- A400 cable (DB37 to 4 × DB25 male connectors)
- A640 cable (DB37 male to DB37 female, for RS4232-4 isolation box connection)
- RS4232-4 isolation box (for isolated RS232/RS422/RS485 conversion)
- TB485 converter (DB9 to 3-pin terminal block for RS485 wiring)

Connectors:
- On-board: DB37 female
- Cable outputs: 4 × DB9 male (RS422/485 signal)

Pin Assignments (DB9):
- Pin 1: DCD (In)
- Pin 2: RXD+ (In)
- Pin 3: TXD+ (Out)
- Pin 4: TXD− (Out)
- Pin 5: GND (Isolated)
- Pin 6: RXD− (In)
- Pin 7: RTS (Out)
- Pin 8: CTS (In)
- Pin 9: RI (In)

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### 6. Installation & Setup

System Requirements:
- PC/AT compatible system with available PCI slot (3.3V or 5V, 33 MHz)
- Supported operating system (DOS, Windows, Linux, SCO)

Installation Steps:
1. Power off the system and unplug it.
2. Insert the P485U card into an available PCI slot.
3. Connect the A404 cable to the DB37 connector on the card.
4. Secure the cable and card in place.
5. Power on the system.
6. Install the appropriate driver for your operating system.

Jumper & DIP Switch Configuration:
- JP1: Card number selection (ON = first card, OFF = second card).
- SW1 (4-bit DIP switch):
- Bit 1: Port A mode (ON = RS422, OFF = RS485)
- Bit 2: Port B mode (ON = RS422, OFF = RS485)
- Bit 3: Port C mode (ON = RS422, OFF = RS485)
- Bit 4: Port D mode (ON = RS422, OFF = RS485)
- JP2, JP4, JP6, JP8: Termination resistor insertion (120 Ω).
- Shorted = terminator inserted
- Open = terminator removed (default)

Driver Installation:
- Windows 2000/XP: Plug & Play detection; specify driver path (A:\WIN2000).
- Windows NT4: Manual installation via Control Panel → Network → Add Adapter → “Other” → specify A:\P584\NT4.
- Windows 95/98/ME: Plug & Play detection; specify A:\WIN95.
- DOS: Run `PCIPORT` from the driver diskette or copied directory.
- Linux: Copy driver source to `/etc/rayon`, run `./Install`, rebuild kernel modules.
- SCO OpenServer: Use `/etc/custom` or manual `tar` and `build` procedure.

Multi-Card Installation:
- Up to two P485U cards per system.
- One card must have JP1 ON (first card), the other OFF (second card).
- IRQ sharing supported under Windows and Linux; separate IRQs required under SCO.

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### 7. Performance & Capabilities

- Data Rate: 50 bps to 115.2 kbps (standard), up to 921.6 kbps (optional crystal).
- FIFO Buffer: 16-byte transmit and receive per port.
- Interrupt Handling: Shared IRQ, PCI BIOS assigned.
- Throughput: Optimized for reduced CPU load via buffered UARTs.
- Maximum Cards per System: 2 (8 ports total).
- Signal Isolation: Common ground per card; isolated ground per port via cable design.
- Termination: Optional 120 Ω resistors per port for long-distance or high-speed RS485 networks.
- Limitations:
- RS485 mode is half-duplex only.
- RS422 mode supports full-duplex but limited to one active driver per line.
- Total cable length depends on baud rate and cable quality (typically up to 1200 m at 9600 bps).

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### 8. Standards & Compliance

- PCI Specification: Revision 2.1 compliant
- Electrical Interface: EIA/TIA RS422 and RS485 standards
- Controller Compliance: Broadcom/PLX PCI9030 ASIC
- Operating System Drivers: Certified for Windows 95/98/ME/NT/2000/XP, Linux, SCO OpenServer
- EMC & Safety: Designed to meet CE and FCC Class A industrial standards (manufacturer dependent)
- Environmental Compliance: RoHS (for later production batches)

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### 9. Additional Information

Warranty:
- 1-year limited warranty covering defects in materials and workmanship.
- Excludes damage from misuse, electrical surges, or unauthorized servicing.

Support & Service:
- Europe:
Acceed GmbH, Arnoldstraße 19, 40479 Düsseldorf, Germany
Tel: +49 211 938898 0
Email: rayon@acceed.com
Web: [www.acceed.com/rayon](http://www.acceed.com/rayon)

- Taiwan:
Rayon Technology Co. Ltd., 2F, No. 177, Chung-Shan 2 Road, Lu-Chou City, Taipei Hsien, Taiwan R.O.C.
Tel: +886 2 82858362
Fax: +886 2 82857065
Email: rayon@ms1.hinet.net

Maintenance:
- Periodically inspect connectors and cables for wear or oxidation.
- Ensure proper grounding and termination for RS485 networks.
- Avoid hot-swapping; always power down before inserting or removing the card.

Repair & RMA Procedure:
- Contact RAYON support for Return Material Authorization (RMA).
- Provide model number, serial number, and fault description.
- Warranty repairs are free; out-of-warranty repairs incur a flat-rate service charge.

Software & Updates:
- Updated drivers and documentation available via RAYON or Acceed websites.
- Linux driver source provided for kernel integration.

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### Summary

The RAYON P485U is a robust, high-performance 4-port RS422/RS485 PCI communication card engineered for industrial and embedded applications requiring reliable, multi-channel serial connectivity. Its universal PCI interface, intelligent UART buffering, and flexible configuration options make it suitable for a wide range of automation, control, and data acquisition systems. With comprehensive driver support across major operating systems, plug-and-play installation, and optional isolation accessories, the P485U delivers both versatility and stability in demanding serial communication environments.

Key Advantages:
- Universal PCI (3.3V/5V) compatibility
- Four configurable RS422/RS485 ports
- Auto Data Direction Control for RS485
- 16550A UARTs with FIFO buffering
- Multi-OS driver support
- Industrial-grade reliability and expandability

Ideal for:
System integrators, industrial automation engineers, and OEM developers requiring dependable multi-port serial communication in PCI-based systems.