A maintenance item is a Data Item that is configured for use by the Maintenance application to determine if and when an asset is due for maintenance. The Maintenance application processes maintenance items based on the type you select when configuring them. The three types of maintenance items are
Incremental
- An incremental maintenance item is a delta value; it contains the
difference in the value received from the previous value received
for the data item. For example, if the first value received is 1 and
the second value is 5, the incremental maintenance item contains the
value 4. If this type of maintenance item is associated with a counter,
a reset of the counter to zero causes the value of the item to be
set to zero. For example, suppose a counter represents the number
of machine cycles and is reset to zero when the machine is powered
off. The counter returns the values as follows:
1, 2, 3, 4
Off (reset to 0, -4)
1, 2, 3
Off (reset to 0)
1, 2, 3, 4, 5
The value of an incremental
maintenance item associated with this counter is calculated as follows:
4 - 4
(the reset to zero) + 3 - 3 + 5, for a total of
5
If you want to know the
total number of machine cycles, use the Counter type instead.
Cumulative - A cumulative maintenance item contains the actual total of all values received for the data item. The value rises as new positive values are received and falls as new negative values are received. For example, if the first value received is 1, the second 2, the third 3, and the fourth -2, the cumulative maintenance item
Counter
- A counter contains a cumulative value, without subtracting all values
when the counter is reset to 0. For example, a counter might represent
the number of machine cycles and, when the machine is powered off,
is reset to zero. The Counter returns the values as follows:
1, 2, 3, 4
Off
(reset to 0)
1, 2, 3
Off
(0)
1, 2, 3,
4, 5
The value of this
maintenance item is calculated as follows:
4
+ 0 + 3
+ 0 + 5
= 12
For information about security for maintenance items, refer to Security for Objects in Axeda® Connected Product Management Applications and for information about security for these objects when Delegated Administration is enabled, refer to Security for Objects in Delegated Administration Units.