DPU Bus Troubleshooting
Metso Automation MAX Controls
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The verification procedure described above can be used during DPU Bus
cabling. In this case the verification period is 12 hours. It is not necessary to
IGAP the system and a printout is not needed. This procedure can also be
used to isolate DPU Bus problems if they occur. The verification procedure
should be performed under the ideal conditions indicated earlier in this
chapter. Once a system is on line, it may be extremely difficult to perform
verification procedures under ideal conditions. If less than ideal conditions
exist, refer to Table 2-1 when reviewing performance results.
Table 2-1-Condition Effects on Performance
Less than Ideal Condition
Effects on Results
Non-blank DPU and
operating conditions displays.
Retries and status broadcasts may be
greater than 0.
Non-IGAP’d network.
Retries will be greater than 0.
Process or System Alarms.
Status broadcasts will be indicated
from stations reporting alarms.
DPU Bus Maintenance
Routine maintenance is not required for a DPU Bus. However, the
verification procedure should be performed every one to two years at a time
when the system can be placed off-line for a period of 12 to 24 hours.
Current verification data compared with the original startup verification data
will indicate whether any DPU Bus performance degradation has occurred.
If system performance has degraded, refer to Chapter 4, “Troubleshooting
Tips and Pointers.”
Check the 24 Volt power supply at initial system startup and at least once a
year thereafter. Ascertain that the unit is operating at a steady 24 V +4 V, -2
V dc with low AC ripple.
