Metso DNA system troubleshooting

Power supply voltage check: ACN MR requires 18-36 VDC, with a typical power consumption of 10 W. Measure the power terminals on the MBMT120 or MBMT80 mounting base, and the voltage fluctuation should be less than 5%. In redundant configurations, it is best for two controllers to be powered by independent power modules.

Ethernet communication diagnosis: ACN MR has five Ethernet ports: four 10/100Base-T (for inter node communication and I/O bus), and one 1000Base-T (for redundancy). Use the Ping command to test the controller IP address (obtained from the node list of DNA Operate). If not, check the switch port VLAN settings and cable type (direct/cross). Note: ACN MR does not have a serial console, and the only way to restore network configuration is to use an SD card to reset to factory settings.

Viewing real-time operating system logs: Connecting the monitor to the USB port of ACN MR? Actual ACN MR has no video output. A more professional approach is to enter RTOS maintenance mode through Ethernet using SSH (requiring Metso engineering privileges) and check for startup errors in/var/log/messages. Common errors include 'Failed to mount SD card' or 'License key mismatch'.

Solution:

If the SD card is damaged, use the D201915 ACN MR Node license to remake the SD card, ensuring that it includes the node configuration and process controller capacity license (D200990 per 100 I/O).

If the controller hardware fails, replace the ACN MR unit (40 × 125 × 95 mm, 1.1 GHz Atom processor). When reinstalling, please note that the MBMT120 (for M120 I/O) and MBMT80 (for M80 I/O) bases are different and cannot be mixed.

When the redundancy switch fails, manually force the switch: click "Force Switchover" in the redundancy panel of the DNA Operate controller. If it still fails, check whether the application versions of the two controllers are completely consistent (including the functional block diagram version).

4.4 Spectrum anomalies or inability to identify bearing defect frequencies in analysis tools

Phenomenon: In the Machine Monitoring analysis tool, a large number of unknown peaks appear on the spectrum, or known bearing fault frequencies (such as BPFI, BPFO) are overwhelmed by noise, and cursor movement cannot automatically jump to the calculated defect frequency position.

Troubleshooting steps:

Confirm that the RPM input is correct: In the "Rotational frequency" area of the analysis tool (page 45 of the PDF), check the currently displayed RPM value. If it is manually input, it needs to be consistent with the actual device speed; If it is a trigger signal from AIF8T, check if the trigger source is stable. Pressing the cursor button will automatically mark the positions of 1 ×, 2 × and other harmonics on the spectrum. If the marked positions do not match the expected values, it indicates that the speed reference is incorrect.

Verify bearing database and configuration: Click on "Bearing information" (PDF page 45) to ensure that the current measuring point is associated with the correct bearing model. Metso DNA contains a database of bearing defect frequencies (such as SKF, FAG) internally. If it is not displayed, you need to enter the Machine Structure Editor (PDF page 52) to manually add the bearing type, number of teeth, and transmission ratio. For example, for ball bearings, parameters such as pitch diameter, ball diameter, and contact angle need to be entered, and the system will automatically calculate BPFI, BPFO, BSF, and FTF.

Handling gear mesh frequency: For gearboxes, check if the number of gear teeth is correct in the "Gearmesh frequency" area. If there is sideband modulation (with 1 or 2 RPM intervals), it usually indicates tooth wear or uneven load. The "Sideband" marking mode in the toolbox (PDF page 48) can automatically position the cursor to the main engagement frequency and its sidebands.

Choose the correct signal processing path: In the analysis tool, users can select "time signal ->acceleration spectrum ->velocity spectrum ->envelope signal ->envelope spectrum" (PDF page 47). For early bearing failures, envelope demodulation should be used. Enter the Toolbox, select the "Signal" mode, set the upper and lower frequency limits of the bandpass filter (e.g. high pass 2 kHz, low-pass 10 kHz), and then generate the envelope spectrum. At this point, the fault characteristic frequency will be significantly prominent.

Check Waterfall Trend: If the fault is intermittent, you can call Waterfall to view the spectral evolution of multiple measurements. Select "Waterfall functions" in the "Browsing" area (PDF page 47) and observe the changes in frequency components over time. For example, a slow increase in amplitude of 1 x in hold mode indicates imbalance; And a sudden jump in BPFO amplitude indicates bearing spalling.

Solution:

If the RPM input is unstable, it can be changed to read the speed from PLC/DCS through OPC, or an independent proximity switch can be added to connect to AIF8T.

For bearing frequencies that cannot be automatically recognized, manually calculate and use "Marker functions" to add a fixed frequency cursor, and save the cursor as a user template.