The ASDU 205 counters are derived from the corresponding IEC 61850 counter objects. Due to range differences, the scaling of the IEC 61850 counter objects are not similar to the expected ASDU 205 scaling. With the default settings the difference is approximately:
ASDU 205 value = 0.2684 × IEC 61850 counter value
Information about how interpret the IEC 61850 counter values in turn are found elsewhere in the IED documentation.
The scale factor is the quotient between the maximum range values of the different counter types.
ASDU 205 counter range is 0…268435455 (0…0×0FFFFFF)
IEC 61850 counter range is 0…999999999 (0…0×3B9AC9FF)
For calculation purposes, the IEC 60870-5-103 protocol needs to know the source counter roll-over value. The roll-over values can be defined through the Communication Management tool Scale value. Default setting is 1000000000 (999999999+1).