KONGSBERG BWMS system operation and maintenance

KONGSBERG BWMS Bridge Duty Monitoring System: Complete Guide to Installation, Debugging, and Troubleshooting

In modern ship bridge management, ensuring that the bridge is always manned is a key step in preventing accidents such as collisions and grounding. The International Maritime Organization (IMO) has clarified the performance standards for Bridge Navigation Duty Alarm Systems (BNWAS) through MSC. 128 (75) resolution, particularly for vessels operating on a single bridge, which must have reliable activity monitoring and alarm transfer capabilities. The Bridge Watch Monitoring System (BWMS) launched by Kongsberg Maritime is a professional solution that meets this requirement.

However, any electronic system that operates at sea for a long time will face issues such as aging, false alarms, communication interruptions, or configuration errors. For engineers and electronic and electrical personnel, mastering the installation and debugging points, daily operation procedures, and quick troubleshooting methods of BWMS is the core skill to ensure navigation safety and reduce unplanned shutdowns. This article is based on the technical specifications and practical application experience of BWMS, systematically sorting out the complete knowledge system from hardware installation to software configuration, from duty logic to alarm linkage, and providing troubleshooting steps and maintenance suggestions for typical faults.

Overview and Core Functions of BWMS System

2.1 Design Objectives and Compliance

BWMS is an intelligent monitoring system specifically designed to monitor the activity status of bridge personnel. When there is no one on duty on the bridge or the on duty driver loses the ability to operate due to health reasons, the system first emits an audible and visual alarm locally on the bridge. If there is no response, the alarm will be automatically transferred to the captain or other qualified backup navigator. This design fully complies with the technical requirements of IMO MSC. 128 (75) for BNWAS and is applicable to all types of vessels, especially those that have obtained the "one person bridge" classification symbol.

2.2 Main Function List

Central bridge alarm panel: Centralized display of visual and auditory alarms from various navigation devices and systems (such as radar, electronic chart, autopilot).

On duty status monitoring: Automatically detect whether there is personnel operation response in the bridge building based on configurable time intervals. If there is no interaction after the timeout (such as buttons, touch screen clicks, or radar/CDIS operations), the system will determine that there is no one on the bridge or the driver is disabled.

Hierarchical alarm transfer: The first level alarm is triggered locally in the bridge unit; If it is not confirmed or reset within the specified time, the second level alarm will be automatically sent to the captain's cabin or designated location; If there is still no response, further call the backup navigator (such as the first mate or second mate). The transfer path and delay time can be customized.

Manual call for backup navigator: The on duty driver can initiate a call for backup personnel at any time through dedicated buttons on the bridge deck panel without waiting for timeout.

Hardware composition and technical specifications

3.1 Core modules

BWMS adopts a modular design, and the main hardware includes:

Bridge alarm panel: human-machine interaction core, including LCD display, status indicator lights, buzzer, function buttons (system start stop, mute/confirm, timer adjustment, backup call, etc.). The panel supports desktop, ceiling, wall bracket or embedded installation (fixed by hidden screws in corners).

Distributed Processing Unit (DPU):

RDi-32: Input processing unit, used to collect external sensor signals (such as buttons, motion detectors) or alarm contacts from other devices.

RDo-16: Output type processing unit that drives external alarm light bells, relays, or sends signals to the onboard alarm management system.

Midi operation station (MOS-33): a terminal used for system configuration and parameter adjustment, usually placed in the control room or electrical room. Through MOS, advanced operations such as defining the number of navigators, editing alarm description text, and setting alarm grouping logic can be completed.

Power Switching Unit (PSO AD-00479): Automatically switches to the backup DC power supply when the main power supply loses power or fluctuates, ensuring uninterrupted operation of the system.

3.2 Detailed Electrical and Environmental Specifications

Parameter indicators

Supply voltage 18-32 VDC, allowable ± 5% ripple

Typical power consumption 26 W

Working temperature -15 ℃ to+70 ℃

Maximum humidity of 96%, no condensation

EMC compliance IACS E10, IEC 60945 4th edition

The protection level depends on the installation method of the panel, and the front is usually IP22 or higher

3.3 Classification Society Type Certification

BWMS has been recognized by mainstream classification societies worldwide, including DNV, BV, GL (now merged with DNV), RINA, NK, ABS, KR, PRS, MRS (Russian Classification Society), CCS (China Classification Society). This means that the system can be directly installed on any vessel flying any relevant flag without the need for additional testing.

Installation and Wiring Engineering Specification

4.1 Selection of installation locations for bridge alarm panels

It should be installed near the main steering console or navigation workstation, within the range where the duty driver can see and operate with their hands when working normally.

Avoid direct exposure to sunlight, heat source radiation, or direct blowing from air conditioning vents, as this may affect the lifespan of internal circuits or trigger temperature alarms incorrectly.

Sufficient space should be reserved on the back of the panel for wiring and later maintenance; During embedded installation, anti loosening washers should be used for the fixing screws under the four corner decorative cover plate.

4.2 Cabinet layout of distributed processing units

RDi-32, RDo-16 and other DPU units are usually assembled on DIN rails inside the bridge console or in separate junction boxes. Notes:

The communication between DPU and bridge deck panel should use twisted pair shielded cables (recommended Belden 8760 or similar), with a maximum distance of 300 meters.

The dry contact signal line of the input/output terminal should be laid separately from the power cable, with a spacing of at least 200mm, to avoid electromagnetic interference.

Each DPU needs to be assigned a unique address dip switch and registered in MOS-33.

4.3 Power Wiring Requirements

BWMS requires a stable 18-32V DC power supply, and it is recommended to lead a dedicated branch from the 24VDC emergency distribution board and connect it in series with a 5A slow melting fuse. Due to the inclusion of alarm buzzers and relay outputs in the system, the instantaneous starting current can reach 3A, and it is necessary to ensure that the line voltage drop does not exceed 5%. It is recommended to use flame-retardant marine wires with a cross-sectional area of ≥ 1.5mm ². If the ship already has a 24V battery pack, it should be connected through a PSO switching unit to achieve undisturbed conversion between the main/backup power supply.

4.4 Grounding and Shielding

The system's common reference ground should be reliably connected to the ship's main grounding copper bar through M5 bolts. All communication cable shielding layers adopt single ended grounding (only grounded at one end on the bridge deck panel side or DPU side to avoid ground circulation). When not properly grounded, it may manifest as random false alarms or panel display garbled characters.

System settings and parameter configuration

5.1 Initial setting through MOS-33

At the factory, BWMS comes pre installed with the basic firmware of Kongsberg Maritime. The end user needs to complete the specific definitions of the following projects through MOS-33:

Number and level of navigators

In the MOS menu "Crew Setup", enter up to 8 reserve personnel, including Captain, First Officer, Second Officer, etc., and assign priorities (e.g. Level 1 for Captain, Level 2 for First Officer). Each personnel needs to associate an alarm trigger output point (such as a buzzer or information terminal connected to their living quarters).

Alarm description and grouping

The text display of each alarm source can be customized (such as "radar failure", "ECDIS out of step", "autopilot heading deviation") and classified into alarm groups (such as "navigation equipment group", "propulsion monitoring group"). When any alarm is triggered within the same group, the main panel displays it according to the group classification for quick positioning.

Timer parameters

Local Alarm Delay: The time from detecting no one on the bridge to triggering the local sound and light alarm, usually set to 12-30 seconds (IMO recommends no more than 30 seconds).

Master Alarm Delay: The time it takes for a local alarm to be transferred to the captain after it has not been confirmed, usually set to 1-3 minutes.

Third level delay (Backup Alarm Delay): Call the backup navigator after the captain has not responded, recommended for 2-5 minutes.

The above parameters are password protected and can only be modified by authorized electronic electricians or ship captains.

Recovery Mode

Set whether the system automatically clears the alarm sequence and resets the timer when the bridge resumes human activity (such as pressing any confirm button or detecting radar/CDIS operation).

5.2 Tool free on-site debugging

Thanks to the pre programmed architecture, most configurations do not require dedicated debugging software. Engineers only need to follow the "AD-00482 BWM Setup Manual for end user" document provided with the equipment and complete all settings through MOS's wizard interface. If you need to adjust the backlight brightness or buzzer volume of the main panel itself, you can enter it through the hidden menu on the panel (long press 【 Silence 】+【 Acknowledge 】 for 5 seconds).

On duty monitoring logic and operation guide

6.1 On duty detection mechanism

BWMS uses the principle of "activity timeout" to determine whether the bridge building is properly guarded. The system continuously monitors the following two types of events:

Explicit interaction: The on duty driver actively presses the "I'm on watch" button on the bridge deck panel or triggers it through a connected motion sensor (such as an infrared motion detector).

Implicit interaction: Read user input from navigation devices (radar, ECDIS, autopilot) connected to BWMS, such as turning the radar's azimuth knob, changing the display scale of the electronic chart, or adjusting the heading setting of the autopilot. Once any interaction is captured, the internal timer is immediately reset to 0.

When the timer accumulates to the set "first level delay" threshold and no interaction occurs, the system determines to enter the "potential unmanned" state.

6.2 Classification alarm transfer process

Stage 1- Local Reminder: The bridge alarm panel emits a buzzing sound (approximately 85dB) and flashes a red light, while displaying "Bridge Unattended - Please Respond". At this time, the on duty driver should press the 'Acknowledge' button on the dashboard or operate any networked navigation device within 30 seconds. If successful, the timer will reset and everything will return to normal.

Stage 2- Call Captain: After the local reminder timeout, the system automatically triggers the output relay, connects the sound alarm installed in the captain's bedroom/dining room, and sends text to the captain's portable reminder device (if integrated). The captain can respond remotely through a dedicated "takeover" button or rush to the bridge for confirmation. After the response, the system will reset and will no longer continue with the upgrade.

Stage 3- Call the backup navigator: If the captain does not respond within the set time, BWMS activates the third level output and sends an alarm to the residences of the first and second officers until someone responds.

6.3 Manual call backup function

During regular duty hours, if the duty driver needs to temporarily leave the bridge building (such as the restroom or retrieve documents) or feels unwell, they can press the 【 Call Backup 】 button on the dashboard. This will immediately bypass stages 1 and 2 and directly call the backup navigator with the highest priority to come and provide support. This operation is not considered an alarm fault, but it is recorded in the ship safety log.

Common troubleshooting and repair cases

7.1 Fault 1: Frequent false alarms on bridge deck panels (triggered when no one is present)

Phenomenon: Even though VDR playback shows that there is always someone operating the bridge, the system still prompts "Unattended" every few minutes.

Possible reasons:

The installation position of the motion sensor is unreasonable, covering blind spots or being too far away from the main operating position.

Implicit interaction signal not properly connected - radar/CDIS did not send heartbeat or button pulses to BWMS.

If the timer is set too short (e.g. 5 seconds), the driver will be judged as pausing if they do not check the chart normally for a few seconds.

Solution steps:

Check the "Activity Sources" page in MOS-33 to see which interaction device was last detected. If 'None' is displayed, it indicates that BWMS has not received any external input.

Temporarily increase the first level delay of the timer to 45 seconds (for testing purposes) and observe if frequent alarms still occur. If not reported, the original set value is too short and should be set to 15-20 seconds according to the actual working pace.

Check sensor wiring: The infrared motion detector should be installed near the driver's head when seated normally, and avoid the air conditioning outlet (to avoid mistaking airflow for movement). The detector output normally open contact should be connected to the DI terminal of RDi-32.

For integration with radar/ECDIS, it is necessary to ensure that the baud rate of the serial communication between devices (NMEA 0183 or NMEA 2000) matches, and the message format is "$IIACK *". Data can be captured using the "Communication Monitoring" tool within MOS.

7.2 Fault 2: Alarm transfer cannot trigger the captain's cabin alarm

Phenomenon: The local alarm on the bridge tower prompts normally, but after exceeding the time limit, there is no sound or light signal at the captain's location.

Possible reasons:

The output relay (RDo-16 corresponding channel) is damaged or the wiring is loose.

The captain's cabin alarm itself is malfunctioning (such as a burnt buzzer).

The 'Level 1 output' is not correctly associated with a specific physical output point in MOS.

Solution steps:

Enter MOS-33 "Output Test" mode and force the relay of the corresponding port on RDo-16 to be activated. If you can hear the sound of the relay action and measure its contact continuity with a multimeter, then the output board is normal; Otherwise, replace the DPU.

Check if there is any open or short circuit in the cable from the output terminal to the captain's cabin alarm. Measure the control voltage at the alarm terminal (should be 18-32V). If there is no voltage, search for the intermediate junction box.

Reconfigure alarm mapping in MOS: Under the "Alarm Routing" menu, select "Master Level" and check the actual physical output channel number.

7.3 Fault 3: The system cannot power on or intermittently restarts

Phenomenon: The bridge deck panel is black or randomly restarted during normal operation.

Possible reasons:

The DC power supply voltage is lower than 18V (such as being powered by batteries or experiencing excessive voltage drop in the line).

Power Switching Unit (PSO) malfunction, internal relay shaking.

The electrolytic capacitor on the main control board is aging.

Solution steps:

Measure the voltage at the power supply terminals of the bridge deck panel. If it is between 15V and 17V, check if the 24V charger output on board is normal and increase the cross-sectional area of the wire. If the voltage is higher than 32V, it indicates that the voltage regulator has failed, and the power should be immediately disconnected and replaced.

Temporarily bypass the PSO and connect directly to a stable 24V battery pack. If the system is restored to stability, the PSO is faulty. Refer to document AD-00479 to replace the PSO module.

For old batches of equipment, if the capacitor bulges or leaks, contact Kongsberg after-sales for board level repair.

7.4 Fault 4: MOS-33 cannot connect to DPU or bridge panel

Phenomenon: "Comm Error - No Response from Bridge Panel" is displayed on the operation station.

Possible reasons:

Communication cable open circuit or wiring error (A/B wires reversed).

The terminal resistance is not set correctly (in the case of CAN fieldbus).

DPU address conflict.

Solution steps:

Check if the CAN-H and CAN_L wires are correctly connected to all nodes and if the shielding layer is well grounded. The terminal resistor should be connected in parallel with a 120 Ω resistor at each end node of the bus.

Check the dip switch of each DPU to ensure that the address is unique and consistent with the MOS configuration table.

Measure the differential signal voltage using an oscilloscope. During normal idle, CAN-H is about 2.5V to ground and CAN_L is about 2.5V; during communication, the two change in phase. If there is no signal, the main controller is damaged.

Regular maintenance and recommendations for extending lifespan

8.1 Monthly inspection items

Clean the screens and buttons on the bridge deck to prevent poor contact caused by salt spray crystallization.

Test all alarm transfer paths: manually trigger the "unmanned" simulation to confirm that the captain and backup navigator can receive the actual alarm.

Measure the power supply voltage and record it in the engine log. If it drops more than 0.5V compared to the last time, check the circuit or power module.

8.2 Annual Plan

Remove the panel and check for oxidation or looseness in the internal connectors; Apply anti loosening glue to the fasteners.

Use dry compressed air (≤ 3bar) to blow away dust inside the DPU cabinet.

Backup all current configuration parameters to a USB flash drive or laptop through MOS-33 to prevent the need for recovery during device replacement.

8.3 Suggestions for spare parts

According to equipment failure statistics, the following spare parts should be kept on board:

1 bridge deck main control panel (spare part number can be obtained from the label)

2 RDo-16 output DPUs (as relays are vulnerable components)

1 PSO power switching unit

Several 5 × 20mm slow melting fuses (5 each for 2A and 5A)

Differences from the old version of BNWAS and upgrade precautions

Some ships are still using the previous generation BNWAS (which only has a simple timing reset function and no graded alarm transfer or implicit interactive detection). When upgrading to Kongsberg BWMS, please note:

The original alarm light bell can be reused, but it needs to be connected to the RDo-16 output module.

If the original system does not have a motion sensor, it is necessary to install a PIR probe recommended by Kongsberg and adjust the installation angle.

The NMEA interface with the newly installed radar/ECDIS may require a converter (such as RS422 to CAN), it is recommended to contact the original factory to obtain the adapter box.

After completing the upgrade, it is necessary to conduct IMO compliance testing again: simulate driver incapacitation, measure the actual triggering time from timeout to the second level alarm, and ensure that the deviation from the set value does not exceed ± 5%.