XYCOM XVME-402 Product Description

I. Product Overview

XVME-402 is a 3U single-height VMEbus four-channel mixed serial communication module launched by XYCOM (now affiliated with Acromag/Xembedded). As an upgraded compatible model of XVME-400 (RS-232C) and XVME-401 (RS-422A/RS-485), it can support RS-232C / RS-422A / RS-485 three electrical interfaces through configuration. It is specifically designed for industrial multi-protocol, mixed interface, long-distance and high-interference resistance communication scenarios, suitable for VME architecture measurement and control, data acquisition, device networking and upgrading of old systems. This module has been officially discontinued. The market circulation is mainly in the form of second-hand, refurbished and inventory spare parts. The standard order number is 70402-001.Core Positioning

As a VMEbus device, XVME-402 focuses on "4 independent configurable serial ports + three interface compatibility + multi-protocol communication + each channel independent baud rate + interrupt-driven + wide temperature high reliability". A single slot can achieve flexible switching of three serial port electrical standards, solving the pain points of inconsistent interface in industrial field equipment, large communication distance and strong anti-interference requirements, suitable for mixed interface equipment interconnection, long-distance differential communication and coexistence of short-distance standard serial port communication in complex scenarios.

II. Core Functional Characteristics

1. Standard VMEbus Interface (fully compatible design)

Fully complies with IEEE 1014 VMEbus specification, compatible with all 3U VME chassis and backplanes, operating in device mode. The address space supports A16 (64KB), fixed occupying 1KB address window, base address is flexibly configured through onboard jumpers to avoid system address conflicts. Data width is compatible with D08/D16, suitable for 8/16-bit VME master controllers. Backplane connection uses P1 connector, compatible with single-height module standard, supports VME 7-level interrupts (configurable priority and vector), can generate 16 independent interrupt vectors, meeting real-time data transmission and fault alarm requirements.

2. 4 Independent Configurable Serial Channels (core function)

Equipped with 2 Zilog Z8530 serial communication controllers (SCC), providing 4 completely independent, software/hardware configurable serial interfaces. Each channel can be set independently as RS-232C (short distance), RS-422A (full-duplex differential), RS-485 (half-duplex differential) three modes, channels do not interfere with each other, and can simultaneously connect different interface types of serial port devices (such as RS-232C terminal, RS-485 sensor, RS-422A PLC).

Communication Mode: Supports asynchronous (ASCII), single synchronous, double synchronous, HDLC/SDLC protocols, compatible with industrial standards and custom communication requirements.

Baud Rate Range: Asynchronous maximum 57.6kbps, synchronous maximum 500kbps, each channel can be independently programmed and set, flexibly matching different device rates.

Electrical Characteristics and Transmission Distance: RS-232C is ±12V level, transmission distance 15 meters; RS-422A/RS-485 is differential level, with high common mode suppression ratio, strong anti-interference ability, the maximum transmission distance is 1200 meters (low baud rate). 

Multi-node Networking: RS-485 mode supports 1 master multiple from (up to 32 nodes) bus networking, compatible with distributed measurement and control system device cascading. Modem Control: Each path provides RTS, CTS, DCD, and DTR hardware handshake signals, supporting standard Modem connections and hardware flow control, ensuring stable data transmission.

3. Flexible Interrupts and Data Reception/Transmission Control

Supports multiple event interrupts, including data reception/ transmission completion, reception errors (parity / frame / overflow), Modem signal status changes, etc. Can mask any channel interrupts. Interrupt vectors can be configured. Suitable for high real-time data transmission scenarios. Interrupt response is fast. Supports DMA or query-style data reception and transmission, meeting the requirements of different system architectures.

4. Industrial-grade High Reliability Design

Standard operating temperature: -20°C to +70°C, storage temperature: -40°C to +85°C, humidity: 5%–95% RH (non-condensing), suitable for industrial sites, outdoor and test equipment, etc. The circuit board uses multi-layer board wiring and gold-plated finger design. Key circuits add noise suppression. Certified by CE/FCC Class A, strong anti-static and anti-interference ability, stable long-term operation.

5. Panel Status Indicator Lights

The front panel is equipped with POWER, RUN, CH0–CH3 TX/RX indicator lights: POWER is always on, indicating normal +5V power supply; RUN is always on, indicating self-check passed and module normal operation; TX/RX corresponding to the channel sending/receiving data flashes, facilitating quick on-site troubleshooting of channel communication status.

III. Hardware Specifications Details

Bus Interface Specifications

Bus Protocol: IEEE 1014 VMEbus, slave device mode;

Address Space: A16 (64KB), 1KB window, jumper configuration base address;

Data Width: D08/D16;

Interrupt Support: VME 7-level interrupts, configurable priority and vector, 16 independent interrupt vectors;

Backplane Interface: P1 connector;

Size: 3U (100mm×233.4mm), single slot;

Weight: Approximately 0.3kg.

Serial Channel Specifications

Channel Quantity: 4 independent configurable RS-232C/RS-422A/RS-485 interfaces;

Communication Controller: 2×Zilog Z8530 SCC;

Communication Mode: Asynchronous, single synchronous, double synchronous, HDLC/SDLC;

Baud Rate: Asynchronous maximum 57.6kbps, synchronous maximum 500kbps;

Handshake Signals: RTS, CTS, DCD, DTR (per path);

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

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: Front panel DB9 or DB25 interface (depending on version).

Electrical and Environmental Specifications

Power Supply: +5V DC ±5%, typical current 1.4A, maximum 1.6A; +12V DC typical current 100mA, maximum 110mA;

Operating Temperature: -20°C to +70°C;

Storage Temperature: -40°C to +85°C;

Anti-Vibration: 5–2000Hz, 2.5g;

Anti-Shock: 30g (working)/50g (non-working);

Humidity: 5%–95% RH (non-condensing);

Altitude: Working maximum 3048 meters, non-working maximum 15240 meters.

IV. Typical Application Scenarios

1. Interconnection of Hybrid Interface Devices It is applicable to scenarios where RS-232C, RS-422A and RS-485 interfaces are present simultaneously in industrial sites, such as connecting RS-232C operation terminals, RS-485 temperature and humidity sensors, and RS-422A PLC. A single module can achieve unified access for multiple types of devices, simplifying the system architecture.

2. Long-distance and short-distance communication coexistence system

Used in factory workshops, rail transit and other areas, close-range (within 15 meters) devices use RS-232C communication, while long-range (1000 meters or more) devices use RS-485 differential communication. The same module can be flexibly configured to balance communication distance and cost.

3. Upgrade of old VME systems with multiple interfaces

Directly replace the serial port module of the old system (such as XVME-400/401) in the system without modifying the chassis architecture and main program. It can be upgraded to have three interface compatibility communication capabilities, suitable for the maintenance of old VME devices in military, aerospace, and industrial control fields, and extending the equipment lifespan.

4. Distributed measurement and control and multi-node bus network

Used in intelligent buildings, production line automation, and energy equipment monitoring. Build an RS-485 bus network, connect access control controllers, alarm hosts, frequency converters, and remote I/O modules, achieving 1 master and 32 slaves device interconnection; at the same time, a RS-232C interface can be reserved to connect a debugging terminal, balancing networking and maintenance requirements.

5. Industrial testing and data acquisition system

Used for industrial testing equipment and data recorders. Connect serial port instruments, encoders, data collectors of different interfaces. Through synchronous communication mode, achieve high-speed data transmission (up to 500 kbps). Differential signals ensure the integrity of long-distance data transmission. Multiple interfaces can adapt to various testing equipment.

Six. Installation and Programming Key Points Installation steps

Preparations: Ensure that the P1 slot of the VME chassis is intact and the +5V/+12V 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).

Jumper configuration: Set the A16 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).

Module insertion: Align the XVME-402 with the 3U 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 the RS-232C device to RX, RX to TX, and connect the ground wire; Connect the A line of the RS-422A/RS-485 device to A line, B line to B line, and connect the ground wire; Connect the shield layer in a single-ended manner 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, and all TX/RX indicator lights are off; When sending data, the corresponding TX/RX flashes, indicating that the module is running normally.

Programming flow (simplified)

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

Channel mode configuration: Write the configuration word to the mode control register, set the type of each interface (RS-232C/RS-422A/RS-485), communication mode (asynchronous/synchronous), baud rate, data bits/parity bits/stop bits, flow control method.

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

Interrupt configuration: Enable interrupts and set the trigger conditions (receiving data, transmission completion, error), and write the interrupt service program to handle real-time data and fault alarms.

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

Six. Core advantages

1. Three interface compatibility, extremely strong adaptability

Single slot integrates RS-232C/RS-422A/RS-485 three interfaces, each path is independently configurable, no need to replace the module to adapt to different interface devices, solving the pain point of inconsistent interface in the field, significantly improving system flexibility.

2. Long distance + High anti-interference, stable in complex environments

RS-422A/RS-485 differential design, the farthest transmission distance is 1200 meters, with high common mode suppression ratio, suitable for industrial strong interference environments; RS-232C meets the short-distance standard communication requirements, balancing distance and anti-interference ability.

3. Multiple protocols + Independent baud rate, flexible configuration

Supports asynchronous, synchronous, HDLC/SDLC and other protocols, each path is independently programmable baud rate, compatible with various serial port devices, suitable for mixed interface communication, long-distance networking, and high-speed data acquisition in multiple scenarios.

4. Industrial-grade wide temperature reliability, adaptable to harsh environments

-20°C to +70°C wide temperature design, resistant to vibration, shock, EMC compliance, suitable for industrial sites, outdoors, equipment vibration and other harsh environments, stable long-term operation, low maintenance cost.

5. Standard VME bus, easy integration and upgrade

Fully compatible with the VMEbus specification, directly compatible with the existing 3U VME system; The configuration is simple and the wiring is convenient. It can directly replace single-interface modules such as XVME-400/401, supporting the upgrade of old systems and the establishment of new systems. It has strong compatibility.

VIII. Notes

The module has been discontinued. When purchasing, prefer to choose second-hand / refurbished spare parts with complete test reports. Check the model 70402-001 and version to avoid faulty or incompatible modules.

The interface can be configured but cannot be mixed simultaneously. 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.

Power supply needs to provide +5V and +12V simultaneously to ensure stable voltage and avoid voltage fluctuations causing communication abnormalities; it is strictly prohibited to reverse the power supply connection to prevent module damage.

When networking with RS-485 bus, both ends of the bus need to be connected with 120Ω terminal resistors to reduce signal reflection; the node address is unique to avoid conflicts leading to communication failures.

The wiring of on-site connection of strong and weak electrical should be separated, the shield layer should be grounded at one end, and it should be far away from strong interference equipment to reduce the influence of electromagnetic interference on the signal and avoid data transmission errors.

The working temperature is -20℃ to +70℃. During installation, ensure that the chassis has good ventilation to avoid overheating; in high-temperature or high-frequency communication scenarios, reduce the baud rate to extend the module lifespan.

During installation and maintenance, take precautions against static electricity, wear an anti-static wristband, and 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.