KONGSBERG Seatex MRU 5 practical combat

7.4 Fault 4: There are a large number of garbled characters or verification errors in the output data

Phenomenon: Intermittent packet corruption, manifested as unresolved hexadecimal characters.

Possible reasons:

The cable shielding layer is not grounded at one end, which introduces electromagnetic interference.

Signal attenuation caused by high baud rate (115200 is not recommended when RS-232 exceeds 15 meters).

No terminal resistor is connected when using RS-422.

Solution steps:

Control the communication distance within 10 meters (RS-232). If a longer distance is required, switch to RS-422 mode and check the differential signal voltage (should be>200mV).

Install a 120 Ω terminal resistor at the RS-422 receiving end.

Add a ferrite magnetic ring (model 31 Material) at each end of the cable to suppress common mode interference.

Regular maintenance and lifespan management

8.1 Monthly Inspection

Clean the connector contacts and spray contact preservatives.

Record the temperature of the sensor (read the internal temperature through MRC). If the difference from the ambient temperature is>8 ° C, there may be an abnormal hot spot inside.

Perform a 'Loop Test': Short circuit TX to RX, send a test command, and verify that the serial hardware is functioning properly.

8.2 Annual Calibration

Although MRU 5 has a nominal drift free design, it is strongly recommended to perform on-site zero bias calibration once a year

When the ship is docked or in very calm sea conditions (heave<0.1m), turn off the power of MRU 5 and let it stand for 30 minutes to stabilize the temperature.

Connect MRC, run "Calibration" ->"gyro bias", and follow the wizard to complete the static gyro bias compensation.

Run the 'Accelerometer Bias' calibration. During the calibration process, do not touch the sensors or move the vessel in any way.

8.3 Suggestions for spare parts

Due to the fact that MRU 5 is a solid-state device with a high MTBF calculation value (over 50000 hours), there is generally no need to keep spare parts for the entire machine. But the following consumables should be prepared:

Special data cable (9-pin D-sub to terminal block, 2 pieces)

Configure cable (USB to RS-232, with FTDI chip)

1A 5 × 20mm fuses (5 pieces)

Firmware upgrade and configuration backup

Kongsberg periodically releases MRU 5 firmware updates, mainly to fix algorithm bugs or add new output protocols. Upgrade steps:

Download the latest firmware (. hex file) and upgrade tool from the official website.

Place MRU 5 in "Bootloader mode": Power off, short circuit the BOOT pin of the debugging interface, and power on again.

Use FlashMagic or Kongsberger's "Seatex Firmware Updating" to flash firmware.

Important: After the upgrade, all configurations will be reset. Be sure to save the backup through MRC's' Save Configuration 'before upgrading. Upgrade and then restore through 'Load Configuration'.