XYCOM XVME-428/1 Product Description

I. Product Overview

XVME-428/1 is a 6U dual-high VMEbus intelligent asynchronous serial communication module (IASCM) launched by XYCOM (now under Pro-face). Equipped with an onboard 68000 processor and intelligent I/O core, it is specifically designed for VME architecture multi-serial port, high real-time performance, and long-distance communication. It can simultaneously provide 8 independent programmable serial ports and is suitable for industrial automation, process control, distributed data acquisition, and upgrading of outdated VME systems. This module has been officially discontinued and is mainly available in second-hand, refurbished, and inventory spare parts in the market. 

Core Positioning

As a VMEbus intelligent slave device, the XVME-428/1 focuses on "8 independent serial ports + three interface compatibility + onboard CPU burden reduction for the host + high-speed programmable baud rate + intelligent line editing + industrial-grade reliability". It features high-density integration of multi-channel asynchronous communication in a single slot, through onboard firmware to autonomously handle serial port transmission and reception, protocol conversion, and data caching. This significantly reduces the load on the main CPU and addresses the core pain points of centralized access for multiple serial devices and long-distance reliable communication.

II. Core Functional Characteristics

1. Standard VMEbus interface (fully compatible with intelligent slave devices)

Complies with the IEEE 1014 VMEbus specification, compatible with all 6U VME chassis and backplanes, operates in intelligent slave device mode, supports A16/A24 address space, fixedly occupying the short address space 0x03800–0x038FF, the base address can be flexibly configured via jumpers to avoid system address conflicts. Data width is compatible with D08/D16, compatible with 8/16-bit VME master controllers, backplane connections use P1/P2 connectors, supports VME standard interrupts and system fault signals (SYSFAIL), compatible with 21-slot VME chassis, plug-and-play.

2. 8 independent programmable asynchronous serial channels (core function)

Equipped with a dedicated serial controller, providing 8 completely independent, software-programmable asynchronous serial interfaces (channels 0–7), each channel can be individually configured as RS-232C (short distance), RS-422A (full-duplex differential), RS-485 (half-duplex differential) or TTL level, channels do not interfere with each other, and can simultaneously connect different interface types of serial port devices (such as terminals, printers, PLCs, sensors, Modems).

Baud rate range: supports 300 bps–3 Mbps programmable, default 9600 bps, each channel independently set, compatible with low-speed instruments to high-speed data transmission scenarios.

Data format: programmable configuration of data bits (5/6/7/8), stop bits (1/1.5/2), parity bits (none / odd / even), default 8N1, compatible with all standard asynchronous communication protocols.

Electrical characteristics and transmission distance: RS-232C transmission distance 15 meters; RS-422A/RS-485 differential level, high common mode suppression ratio, strong anti-interference ability, the farthest transmission distance 1200 meters (low baud rate); TTL level compatible with short-distance communication within the board.

Multi-node networking: RS-485 mode supports 1 master multi-slave (up to 32 nodes) bus networking, compatible with cascading of distributed measurement and control system devices.

Modem control: each channel provides complete hardware handshake signals, supports standard Modem connection and hardware flow control, ensuring stable data transmission.

3. Onboard intelligent I/O core (68000 CPU)

Integrates a 10 MHz 68000 processor and XYCOM exclusive intelligent I/O core, equipped with custom firmware, autonomously handles serial port data transmission and reception, cache management, protocol verification, error handling, and interrupt response, without requiring intervention from the main CPU, significantly reducing the host load and improving system real-time performance. Built-in Terminal Driver Extension (TDE), provides flexible user-configurable intelligent line editing functions, supports local editing, echo control, buffer management, compatible with terminal and interactive device communication scenarios.

4. Flexible interrupts and data transmission control Supports multi-event interrupts, including data reception/ transmission completion, reception errors (parity / frame / overflow), Modem signal status changes, etc. Can mask any channel interrupt. Interrupt vectors can be configured. It is suitable for high real-time data transmission scenarios. Each path has an independent receive and transmit buffer. Supports single-character or full-record transmission. Supports query or interrupt-based receive and transmit. Satisfies the requirements of different system architectures.

5. Industrial-grade high reliability design

Standard operating temperature: 0℃～+55℃. Suitable for harsh environments such as industrial sites and test equipment; The circuit board adopts multi-layer board wiring and gold finger plating design. Key circuits add noise suppression. It has strong anti-static and anti-interference capabilities, and is stable in long-term operation. The front baffle is equipped with status indicator lights, facilitating quick troubleshooting of module operation and channel communication status.

III. Hardware Specifications Details

Bus Interface Specifications

Bus Protocol: IEEE 1014 VMEbus, Intelligent Slave Device Mode;

Address Space: A16/A24, Short Address 0x03800–0x038FF, jumper configuration base address;

Data Width: D08/D16;

Interrupt Support: VME standard interrupt, configurable priority and vector;

Backplane Interface: P1/P2 connectors;

Size: 6U (233.4mm×160mm), single slot;

Weight: Approximately 0.8kg.

Serial Channel Specifications

Channel Quantity: 8 independent programmable RS-232C/RS-422A/RS-485/TTL interfaces;

Communication Controller: Special Asynchronous Serial Controller;

Processor: 10 MHz 68000 CPU, Intelligent I/O Core;

Baud Rate: 300 bps–3 Mbps programmable, default 9600 bps;

Data Format: 5/6/7/8 data bits, 1/1.5/2 stop bits, no / odd / even parity;

Electrical Standards: RS-232C (±12V)/RS-422A/RS-485 (differential)/TTL;

Transmission Distance: RS-232C maximum 15 meters, RS-422A/RS-485 maximum 1200 meters;

Networking Capability: RS-485 supports 1 master 32 slave multi-node bus;

Connector: High-density DB or pin socket interface on the front baffle (depending on version).

Electrical and Environmental Specifications

Power Supply: +5V DC (VME bus power supply), typical power consumption approximately 2W;

Operating Temperature: 0℃～+55℃;

Storage Temperature: -40℃～+85℃;

Humidity: 5%–95% RH (non-condensation);

Anti-Vibration: Complies with industrial standards, suitable for equipment vibration environments.

IV. Typical Application Scenarios

1. Centralized connection of multiple serial devices

Suitable for industrial automation and process control scenarios. Connects 8 serial devices (such as operation terminals, printers, PLCs, instruments, frequency converters) centrally. A single module realizes unified access for multiple devices, simplifying the system architecture and reducing slot occupation.

2. Long-distance distributed measurement and control system

Used in long-distance scenarios such as factory workshops, energy equipment, and rail transit. Through RS-485 bus networking, connects remote sensors, I/O modules, actuators, etc. Differential anti-interference design ensures stable communication in strong electromagnetic environments. The onboard CPU autonomously processes data, improving system response speed.

3. Upgrade of old VME systems with multiple serial ports Directly replace the outdated single-channel serial port module in the old system, without modifying the chassis structure or the main program, and expand to 8 programmable serial ports, supporting RS-232C / differential / TTL multi-interface adaptation. It is suitable for maintaining old VME devices in military, aerospace, and industrial control fields, extending the equipment lifespan.

4. High-speed Data Acquisition and Instrument Interconnection

Used for industrial testing equipment and data loggers, connecting high-speed serial port instruments, encoders, and data collectors. The maximum baud rate of 3 Mbps meets the requirements for high-speed data transmission. Differential signals ensure the integrity of data transmission over long distances. The intelligent core autonomously manages data cache, reducing the pressure on the host.

5. Terminal and Interactive Device Communication

Used for intelligent buildings and security systems. Connecting terminals, consoles, and Modems. Utilizing the built-in TDE intelligent line editing function, it supports local editing and echo control. It is suitable for interactive communication scenarios, enhancing operational convenience.

V. Installation and Programming Key Points Installation steps

Preparations: Ensure that the P1/P2 slots of the VME chassis are intact and the +5V power supply is stable; prepare corresponding cables according to the device interface type (RS-232C ordinary shielded cable, RS-422A/RS-485 twisted shielded cable, TTL flat cable).

Jumper configuration: Set the A16/A24 base address jumper to avoid address conflicts; configure the interrupt priority and vector jumper (if interrupts are needed); set the hardware mode jumper according to the channel interface requirements (RS-232C/RS-422A/RS-485/TTL).

Module insertion: Align the XVME-428/1 with the 6U slot and push it in smoothly to ensure that the gold fingers make good contact with the backplane, and tighten the panel fixing screws.

Cable connection: Connect the TX of RS-232C devices to RX, RX to TX, and ground; connect the A line of RS-422A/RS-485 devices to A line, B line to B line, and ground; connect the corresponding level pins of TTL devices; single-ended ground the shield layer, and keep it away from strong interference equipment such as frequency converters and motors.

Power-on self-test: After the chassis is powered on, the POWER and RUN indicator lights are constantly on, indicating that the module is running normally; the corresponding TX/RX indicator lights flash when the channel transmits and receives data.

Programming flow (simplified)

Address mapping: Configure the A16/A24 base address, map the module control, data, status, and interrupt registers to the system memory, and establish the CPU and module communication channel.

Channel mode configuration: Write the configuration word to the mode control register to set the interface type, baud rate, data format, and flow control mode for each channel.

Intelligent core configuration: Configure the TDE row editing function, buffer size, interrupt trigger condition through the command register, enable the onboard firmware to handle serial port transactions autonomously.

Data transmission: Send/receive data through the data register, support single-character or full-record transmission; read the status register to obtain the channel status (transmit empty, receive full, error flag), support query or interrupt-based transmission.

Interrupt configuration: Enable interrupts and set the trigger conditions, write the interrupt service program to handle real-time data and fault alarms, the onboard core automatically responds to interrupts, without frequent intervention from the host.

Reset operation: When the system/software resets, the module clears the transmission/reception cache, turns off interrupts, and clears flags to ensure communication security.

Six. Core advantages

1. 8 independent serial ports, high-density multi-channel integration

A single 6U slot integrates 8 programmable serial ports, with a large number of channels and high density, a single module can replace multiple low-channel serial port cards, saving chassis slots and hardware costs, and suitable for scenarios of centralized access of multiple devices.

2. Four interface compatibility, extremely strong adaptability

Each channel supports RS-232C/RS-422A/RS-485/TTL modes, software can programmatically switch, without replacing the module to adapt to different interface devices, solving the pain point of inconsistent interface of on-site equipment, significantly improving system flexibility.

3. Onboard CPU relief, high real-time performance

Equipped with a 10 MHz 68000 processor and intelligent firmware, it autonomously handles serial port transmission/reception, cache, and protocol verification, completely liberating the main CPU, improving the overall real-time performance and response speed of the system, suitable for high-load multi-task scenarios.

4. High baud rate + long-distance anti-interference, comprehensive performance

The highest 3 Mbps baud rate meets the requirements of high-speed data transmission; RS-422A/RS-485 differential design, the farthest transmission distance is 1200 meters, with a high common-mode suppression ratio, suitable for industrial strong interference environments, and balancing speed, distance, and stability.

5. Industrial-grade reliability + intelligent editing, easy to use 0℃ to +55℃ wide temperature design, anti-interference, anti-vibration, suitable for industrial harsh environments; built-in TDE intelligent line editing function, simplifies terminal interaction operations, reduces programming complexity, and enhances device usability.

6. Standard VME bus, easy integration and upgrade

Fully compatible with VMEbus specifications, directly compatible with existing 6U VME systems; simple configuration, convenient wiring, can directly replace old single-channel serial port modules, supports upgrading of old systems and building of new systems, with strong compatibility.

VII. Notes

The module has been discontinued. When purchasing, prefer to choose second-hand / refurbished spare parts with complete test reports. Check the model and version to avoid faulty or incompatible modules.

A single channel can only be set to one electrical mode. It is strictly prohibited to connect differential signals in RS-232C mode or connect RS-232C signals in differential mode. Otherwise, the interface circuit will be burned out; the terminals at both ends of the RS-485 bus need to be connected with 120Ω termination resistors to reduce signal reflection.

The power supply is +5V bus power supply to ensure voltage stability and avoid voltage fluctuations causing communication abnormalities; it is strictly prohibited to reverse the power supply connection to prevent module damage.

The wiring of on-site strong and weak electrical separation is required. The shield layer is grounded at one end, away from strong interference equipment, to reduce the impact of electromagnetic interference on the signal and avoid data transmission errors.

The working temperature is 0℃ to +55℃. During installation, ensure good ventilation of the chassis to avoid heat accumulation; in high-temperature or high-frequency communication scenarios, appropriately reduce the baud rate to extend the module lifespan.

During installation and maintenance, take precautions against static electricity, wear an anti-static wristband, operate on an anti-static workbench; before plugging or unplugging the module, cut off the power supply of the chassis to prevent damage to the backplane and module due to live plugging or unplugging.

The onboard 68000 processor firmware is a dedicated program. It is prohibited to modify or flash it at will, otherwise it may cause module functional abnormalities or inability to use.