Program Optimization
Page 6-8 ABB Control - AC 31
1SBC 260400 R1001-b 06.99
2.2. Validation of interruptions
The interruptions may, or may not, be validated (activated) depending on the process.
Once an interruption has been defined the name is automatically placed in the function block
list as a function block
An interruption is validated through the utilization of the function block.
Taking the previous example; the interruptions INT1, INT2 and INT3 are validated in the
following manner in the program:
INT1
EN
INT2
EN
INT3
EN
VALID1
VALID2
VALID3
2.3. Performances
The delay, for considering the interruption, depends on the central unit configuration.
In fact, when the central unit is configured as master the CS 31 bus management has the
highest priority.
AC 31 master central unit AC 31 slave central unit stand-alone central unit
Alarm (hardware interruption) max. time. 2,5 ms max. time 2,5 ms max. time 250 µs
Cyclic interruption min. time. 5 ms min. time 1 ms min. time 1 ms
Max length 1,5 ms 3 ms 3 ms
It is recommended that the DI and DO functions are used when immediate access to physical
inputs/outputs becomes necessary, in an interruption, for immediate information execution
(attention, these functions can only be used for the inputs/outputs of the central unit and its
extensions).
Example: the physical command of an output may be carried out independently of the central
unit cycle time.
The unit cannot effectuate more than one task at a time.
Certain tasks have a higher priority than others.
The descending priority is:
- Communication with a unit on the CS 31 bus
- Interruption on the I62.02 input
- Interruption on the I62.03 input
- Cyclic interruption
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