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changed. Therefore, the N2 system should be set up to disallow overriding BI points or have an alarm
condition activated when a BI point is overridden.
7.2.3
Analogue Output (AO)
All Analogue Output (AO) points have the following features:
•
Support Change of State (COS) reporting based on override status.
•
Always considered reliable.
•
Overriding of the AO points is the method used to change a value. Overriding an AO point with
a value beyond the limit allowed by the drive’s internal variable will result in an ”Invalid Data”
error response and the override status and value will remain unchanged. If the overridden
value is beyond the drive’s parameter limit but within the range that will fit in the variable, an
acknowledge response is given and the value will be internally clamped to its limit.
•
An AO point override copies the override value to the corresponding drive parameter. This is
the same as changing the value on the keypad. The value is non-volatile and will remain in ef-
fect when the drive is turned off and back on. It also remains at this value when the N2 net-
work "releases" the point. The N2 system always reads the current parameter value.
Note:
On some N2 systems, the system will not poll the AO point when it is being overridden. In this case,
the N2 system will not notice a change in value if the change is made with the keypad. To avoid this,
set the point up as a ”local control” type and release it once it has been overridden. In this way, the N2
system will monitor the value when not being overridden.
7.2.4
Binary Output (BO)
All Binary Output (BO) points have the follwoing features:
•
Support Change of State (COS) reporting based on override status.
•
Always considered reliable.
•
Overriding BO points control the drive. These points are input commands to the drive. When
released, the drive's internal value remains at its last overridden value.
7.2.5
Internal Integer (ADI)
All Internal Integer (ADI) points have the follwoing features:
•
Do not support Change of State (COS) reporting.
•
Can be overridden and the ”Override Active” bit will be set. However, the Internal value is un-
changed (Read Only).
