Priority Levels
Overview
When polling devices, higher priority can be assigned to more important items and lower priority to less important items. Priority becomes more important on larger, more congested systems.
ACM will temporarily interrupt the device currently being polled on a port to handle a read or write to this item only if the Interrupt threshold is met.
Priority Examples
opcitem<Wn> to set write priority where n is the priority level, “Device1.40001<W0>”
opcitem<Pn> to set read priority where n is the priority level, “Device1.40001<P2>”
Device1.40001<W0><P2> will be read with High Priority and written with Immediate Priority.
Priority Levels
Priority | Level | Example | Intended Usage |
|---|---|---|---|
0 | Immediate | ItemName<W0> | Highest priority writes. This is the default write priority. |
1 | Demand | N/A | Demand polls (reserved for demand polls, cannot be part of an item name). |
2 | High | ItemName<W2> | This can raise the priority for reads and lower the priority for writes. |
3 | Medium | ItemName<W3> | General reads and/or EFM collection. This is the default read priority. |
4 | Low | ItemName<W4> | EFM Collection. |
Note
Priority levels for reads (2 – 4) and writes (0 – 4), and note that the Interrupt Threshold is configured in the port and that it is a setting that will only allow interruptions on a connection that exceed the configured threshold.