EAU-321 Multi Protocol Serial Port Card

EAU-321 Serial Port Board Integration Guide

In fire alarm and life safety systems, data exchange with third-party devices is one of the most common and challenging tasks in system integration. The Autronica AutoSafe system, as a mature fire alarm control platform, provides a dedicated internal communication protocol AutoCom. However, to interface the system with building management systems, paging systems, or external PLC devices, hardware level protocol conversion and physical interface support are required. The EAU-321 four channel multi protocol serial communication board was born for this purpose - it is a PC/104 specification expansion module that can be installed inside the AutoSafe system unit, providing RS232, RS422, or RS485 interfaces through flexible jumper settings to achieve reliable data exchange with external devices.

This article will provide a detailed interpretation of the technical features, port allocation strategy, jumper configuration method, installation steps, and common application scenarios of EAU-321 from an engineering practice perspective, helping system integration engineers and on-site maintenance personnel quickly grasp the key points of using this module.

Product positioning and core features

EAU-321 is a four channel serial communication board that follows the PC/104 bus standard. Its design goal is very clear: to occupy a small amount of space inside the AutoSafe system unit (fire alarm control panel BS-310/320 or controller BC-320) and provide flexible multi protocol serial port expansion capability.

List of Core Features

Four channel independent serial port: supports simultaneous connection of up to four external devices

Multi protocol support: Ports 1 and 2 can be switched between RS232, RS422, and RS485 through jumper settings; Ports 3 and 4 are fixed RS232 ports

AutoCom redundant communication: Ports 1 and 2 support redundant AutoCom communication, improving the availability of critical links

Special function allocation: Port 3 is reserved for AutoSafe IFG AutoFieldBus communication, and Port 4 is used for downloading AUTROLON network configuration

Compact PC/104 size: 90 × 96mm, can be directly stacked on EAU-310 communication board or EAC300 processor board

Wide temperature range: -40 ° C to+85 ° C, suitable for industrial environments

Short circuit protection: All outputs have continuous short circuit protection capability

These features make EAU-321 not only suitable for standard fire alarm system integration, but also capable of handling industries such as ships, oil and gas that require higher reliability and environmental adaptability.

Detailed explanation of port functions

Understanding the allocation and electrical definition of each port is the first step towards successful integration. The four ports of EAU-321 are not completely equivalent, as they undertake different system responsibilities.

Ports 1 and 2- Multi protocol AutoCom ports

Ports 1 and 2 are the "flexible interfaces" of the system, with the most extensive uses:

Supports three electrical standards: RS232, RS422, and RS485 (selected through jumper)

Mainly used for AutoCom communication, i.e. standard protocol transmission between AutoSafe system and third-party devices

Redundant communication configuration can be achieved: two ports are simultaneously connected to the same third-party device, and when one link fails, it automatically switches, significantly improving the system's fault tolerance capability

In practical engineering, ports 1 and 2 are often configured in the following modes:

RS232 mode: Short distance (<15 meters) point-to-point connection, suitable for old-fashioned serial devices or debugging interfaces

RS422 mode: Long distance (up to 1200 meters) point to multipoint, four wire full duplex, suitable for communication with remote devices such as building management systems

RS485 mode: Long distance multi-point half duplex, supporting up to 32 nodes, commonly used for Modbus RTU bus

Port 3- AutoFieldBus dedicated port

Port 3 is a fixed RS232 interface specifically assigned for AutoSafe IFG AutoFieldBus communication. AutoFieldBus is a bus protocol used within the AutoSafe system to connect field devices such as detectors and input/output modules. The existence of Port 3 allows engineers to diagnose, configure, or collect data directly from the fieldbus through the serial port without going through the main processor.

This port does not support changing the protocol type through jumper cables and always uses RS232. If communication with RS422/485 devices is required, port 1 or 2 should be used in conjunction with an external converter.

Port 4- AUTROLON download port

Port 4 is also a fixed RS232 interface, and its special purpose is for downloading AUTROLON network configuration files. In a distributed system, multiple fire alarm control panels are interconnected through the AUTROLON network. System configurations (such as device databases, logic equations, and linkage schemes) are usually distributed uniformly from the "booting panel". Engineers can download the complete configuration file to the startup panel by connecting port 4 to the configuration computer, and then the startup panel automatically synchronizes to all other panels through the AUTROLON network.

This design greatly simplifies the deployment and maintenance of distributed systems - there is no need to upload configurations panel by panel, and only one download is needed to complete the entire network update.

Definition of Electrical Connections and Terminals

EAU-321 provides signal connection through two 20 bit terminal blocks X1 and X2. Understanding the definition of terminals is the key to proper wiring.

X1 terminal block

X1 corresponds to the signals of ports 1 and 2. The specific definition varies depending on the selected protocol:

RS232 mode (port 1/2):

Pin 1/11: DCD (Data Carrier Detection)

Pin 2/12: DTR (Data Terminal Ready)

Pin 3/13: RXD (receive data)

Pin 4/14: RTS (request to send)

Pin 5/15: TXD (transmit data)

Pin 6/16: CTS (Clear Send)

Pin 7/17: DTR (repeated)

Pin 8/18: RI (Ringing Indicator)

Pin 9/19: GND (signal ground)

Pin 10/20: NC (not connected)

RS422 mode (port 1/2):

Pin 3/13: TxD+(transmit positive)

Pin 4/14: TxD - (transmit negative)

Pin 5/15: GND

Pin 6/16: RxD - (receive negative)

Pin 7/17: RxD+(receive positive)

Other pins NC or not used

RS485 mode (port 1/2):

Pin 3/13: TxD/RxD+(positive data, bidirectional)

Pin 4/14: TxD/RxD - (Data Negative, Bidirectional)

Pin 5/15: GND

Other pins NC

RS485 mode is half duplex, and can only send or receive at the same time. The driving circuit automatically controls direction switching without the need for external RTS control.

X2 terminal block

X2 corresponds to ports 3 and 4, fixed as RS232. The pin allocation is similar to the RS232 mode of X1 (using pins 1-10 for port 3 and pins 11-20 for port 4), including complete DCD, RXD, TXD, DTR, GND and other signals.

Cable recommendations

The PDF specifically states that CAT-5 communication cables can be used. For long-distance applications of RS422/RS485, it is recommended to use shielded twisted pair cables (such as Belden 9841) and ground the shielding layer at one end. For RS232, it is recommended to use multi-core cables with overall shielding, with a maximum length of no more than 15 meters.

Detailed explanation of jumper configuration

The flexibility of EAU-321 largely comes from its jumper configuration. Correctly setting jumper wires is a prerequisite for the normal operation of the module. All jumpers are located on the PC/104 board and should be set up before installation.

J5 and J6- Protocol Selection

J5 and J6 are two multi jumper groups that control the protocol types of port 1 and port 2, respectively. Each port corresponds to a set of jumpers (J5 corresponds to port 1, J6 corresponds to port 2), with multiple independent jumpers inside each set used to define the connection method for each signal.

According to the table provided in the PDF, the jumper modes for each protocol are as follows:

Signal RS232 RS422 RS485

TxOut Note 1 Note 1 Note 1

RxOut Note 1 Note 1 Note 1

CTS Out In In

DCD Out In In

DTR Out In In

R1 Out In In

1 Out In In

2 In Out Out

3 Out In Out

4 Out Out In

5 In Out Out

6 Out Out In

Note 1: The specific jumpers for TxOut and RxOut need to refer to the silk screen of the board or the accompanying quick guide. Usually RS232 uses independent TXD/RXD cables; RS422/485 uses differential pairs.

In practical operation, engineers should refer to the silk screen markings on the EAU-321 board or the jumper diagram in the user manual. The key principle is that RS232 mode requires the connection of single ended signals such as RXD/TXD/CTS/RTS; RS422 mode requires both sending and receiving to be configured as differential pairs; RS485 mode combines sending and receiving on the same pair of differential lines and enables internal direction control.

J8- Interrupt Setting

J8 is used to set the interrupt line. The PDF clearly states that J8 must be set to interrupt 7 and R. This means that EAU-321 will occupy IRQ7 resources. In PC/104 systems, IRQ7 can usually be used for expansion cards, but it is necessary to ensure that there are no conflicts with other devices. If there are multiple communication boards in the system, each board's J8 needs to be set to IRQ7, and different boards need to be distinguished through upper layer software.

J9, J10, J11- Port Interruption

These three jumper groups are used to configure interrupt allocation for each port. The PDF requires all ports to be set to interrupt 7. This means that when any port experiences data reception or a change in line status, the same IRQ7 interrupt will be triggered. The driver program identifies which port caused the interrupt by reading the interrupt status register on the board. This design simplifies interrupt management and is suitable for a polling/interrupt hybrid mode.

J7- Board Address

J7 is used to set the I/O base address of the PC/104 bus. The PDF clearly states that jumper positions A and B must be set to In. This setting applies to all communication boards and corresponds to a base address of 100h (hexadecimal). This means that EAU-321 occupies an I/O address range of around 100h-10Ph (specific mapping depends on internal registers). If multiple EAU-321 cards are installed in the system or have address conflicts with other PC/104 cards, it is necessary to avoid conflicts through other means such as software configuration or different types of cards. However, according to system limitations, each system unit can only support a maximum of one EAU-321, so address conflicts usually do not occur.

Installation and System Capacity Planning

Physical installation

EAU-321 is installed inside the system unit and has two typical installation methods:

Independent system (single panel): directly stacked and installed on the EAC300 processor board. The PC/104 bus is electrically connected through stacked connectors, with EAU-321 located above the processor board and secured with nylon support columns at the four corners.

Distributed system: First install the AUTROLON communication board EAU-310, and then stack EAU-321 on top of EAU-310. In this configuration, EAU-310 is responsible for AUTROLON network communication between panels, while EAU-321 is responsible for serial communication with third-party devices.

In a distributed system, EAU-321 should be installed first in the designated 'Startup Panel', as the AUTROLON download function on port 4 needs to be used on this panel.

System capacity limit

The AutoSafe system has clear capacity limitations for expanding communication boards, and engineers must comply with them when planning:

Scenario 1: System unit without battery

Each system unit can install up to 3 different types of communication boards

Optional combinations: any three of EAU-321 (serial board), EAU-310 (AUTROLON board), EAU-330 (Ethernet board)

If the distributed system requires the installation of EAU-310, the remaining available slots are 2 additional communication boards

Scenario 2: System unit with battery

The battery (usually a backup power source) will occupy some internal space, so only a maximum of 2 communication boards can be installed

If the distributed system requires the installation of EAU-310, the remaining available slots are only one additional communication board

These limitations stem from the power supply capacity and physical space of the backplane, and cannot be over configured. If the project requires more external communication interfaces, consideration should be given to using multiple system units or extending through external protocol converters.

Detailed explanation of technical specifications

Serial port electrical parameters

RS232 mode:

Input impedance: minimum 3k Ω

Input voltage swing: maximum ± 30V (withstand capacity)

Output voltage swing: minimum ± 5V, typical ± 7V

RS422/RS485 mode:

Differential input threshold: -0.2V (minimum) to+0.2V (maximum)

Input impedance: minimum 12k Ω

Input current:+1.0mA maximum (when VIN=12V)

Differential output voltage symmetry: minimum 2.0V between high/low states (when the load resistance is 50 Ω)

Short circuit protection: All outputs have continuous short circuit protection, which will not damage the driver

Bus and power supply

PC/104 bus: Both 8-bit and 16 bit bus connectors are installed simultaneously. The 16 bit connector is mainly used to provide additional interrupt levels.

Power requirement:+5V DC ± 10%

Current consumption: 80mA typical value (when all outputs are unloaded). When multiple external devices are connected and the output drives a large load, the current will increase accordingly, and the total power margin of the system needs to be considered in the design.

Working environment: Temperature range of -40 ° C to+85 ° C, humidity range of 5% to 95% (non condensing). This wide temperature range makes EAU-321 suitable for non temperature controlled environments such as outdoor cabinets and ship deck areas.

Communication parameters (AutoSafe application)

When using the AutoCom protocol within the AutoSafe system, fix the following parameters:

Baud rate: 9600 baud

Data bits: 8 bits

Stop position: 1 position

Verification: None

If a third-party device wants to communicate with AutoSafe through port 1/2, it must be configured with exactly the same parameters, otherwise a valid connection cannot be established.

Typical application scenarios

1. Building management system integration

Building management systems typically exchange status information with fire protection systems through Modbus RTU or BACnet MS/TP protocols. Engineers can configure port 1 or 2 of EAU-321 to RS485 mode and connect it to the serial bus of BMS. AutoSafe, as a slave station, regularly reports the status of fire alarms, malfunctions, isolation, etc; BMS acts as the main station polling data. The redundant configuration of ports 1 and 2 ensures link reliability - when the primary port fails, the system automatically switches to the backup port.

2. Paging system interface

Many paging systems receive trigger signals through the ESPA protocol. EAU-321 is connected to the ESPA interface module via RS232. When the AutoSafe system detects a fire alarm, it sends ESPA format commands through port 1 or 2, and the paging system immediately plays the preset voice alarm information.

3. PLC data exchange

In industrial settings, fire protection systems may need to send fire alarm zone information to DCS or PLC. Through the RS485 port of EAU-321 and in conjunction with the Modbus RTU protocol, AutoSafe can act as a Modbus slave, mapping the status of each detection area to hold registers. The upper PLC periodically reads these registers to achieve linkage between fire protection status and process control.

4. Remote diagnosis and maintenance

By connecting port 3 (AutoFieldBus) to an external GPRS DTU or serial server via RS232, maintenance engineers can monitor the device status on the fieldbus in real-time on a remote computer, perform fault location or firmware upgrades, without the need to physically visit the site.

Troubleshooting and maintenance recommendations

Common problems and troubleshooting steps

Problem 1: Port 1/2 cannot communicate, but port 3/4 is normal

Check if the J5/J6 jumper settings are consistent with the required protocol

Confirm that the communication parameters (9600/8/N/1) of the third-party device match

Check the polarity of cable connections: RS422 requires T+to be connected to the other party R+, T - to be connected to the other party R -; RS485 requires A to be connected to A, B to be connected to B

For RS485 mode, ensure that there is at least one terminal resistor (approximately 120 Ω) on the bus at both ends

Problem 2: Redundant AutoCom does not switch

Confirm that both ports are connected to the target device

Check if the physical link of the backup port is intact when the primary port fails

Verify that the redundancy mode in the AutoSafe system software is enabled

Check if power fluctuations cause the board to reset

Question 3: AUTROLON download failed (port 4)

Confirm that the current panel is the 'Startup Panel' in a distributed system

Check if the serial cable from PC to port 4 is a crossover cable (or using a straight through cable with adapter)

Attempt to reduce the baud rate (although the specification is 9600, the download tool may support other rates)

Confirm that no other software is occupying the COM port

Problem 4: The system cannot detect EAU-321

Check if the PC/104 bus stack connection is secure and if there are any bent pins

Verify if the J7 address jumper is both A/B In (address 100h)

Confirm that the system units have not exceeded the limit of the number of communication boards (with/without batteries)

Measure whether the+5V power supply is within the range of 4.5V-5.5V

Question 5: Intermittent data errors

For RS422/RS485 long-distance lines, check if the shielding layer is single ended grounded

Check if the RS232 cable length exceeds 15 meters

Eliminate strong electromagnetic interference sources (such as frequency converters, high-power wireless transmitters)

Attempt to reduce communication speed (but AutoSafe is fixed at 9600, and third-party devices also need to be adjusted accordingly)

Maintenance Recommendations

EAU-321 uses solid-state circuits with no moving parts, theoretically requiring very low maintenance. However, considering that it is installed inside the fire alarm control panel, it is recommended to check during the annual system testing:

There is no dust accumulation or corrosion marks on the surface of the board

All jumper caps are not loose or oxidized

The terminal block screws are tightened without looseness or copper plating

PC/104 stacked connector without oxidation

The power supply voltage is stable within the range of+5V ± 5%

If there is a suspected hardware malfunction, on-site repair is not recommended. Autronica technical support should be contacted and spare parts should be replaced. The short-circuit protection design of EAU-321 makes it less susceptible to permanent damage due to wiring errors, but repeated overvoltage may damage the ESD protection diode.