Masks & automatic forcing

Masks control monitoring, participation in alarm summaries, acknowledgement requirements, and alarm logging. Choose the setting that matches the operator's intended action.

Select a mask setting

Goal	Setting	What continues
Stop a channel's alarm subscription	Cancel (C)	Other channels continue monitoring.
Exclude a channel from active alarm handling	Disable (D)	Its subscription and alarm-file records continue unless separately cancelled/suppressed.
Remove acknowledgement requirements	NoAck (A)	Monitoring continues.
Do not latch cleared transients	NoAckT (T)	Active alarms remain visible.
Stop a channel's alarm records	NoLog (L)	Monitoring and display continue.

Use Modify Mask (Ctrl+S) or Force Mask (Ctrl+M) for the selected node. Acting on a group applies the change to descendant channels. In passive mode, restricted operations remain unavailable. Global transient-setting writes require IOC write access; failures retain the previous displayed bit and can be retried explicitly.

Canonical configuration order is CDATL. For example, -D--L enables Disable and NoLog; ----- clears all five bits.

Configure a Force PV

To apply a mask automatically when another PV reaches a value, add a $FORCEPV directive to the target group or channel:

GROUP NULL Facility
CHANNEL Facility example:pressure -----
$FORCEPV example:maintenance -D--- 1 0

When example:maintenance becomes 1, Disable is applied. When it becomes 0, the configured channel mask is restored. A group Force PV acts on descendant channels. Use NE as the reset value to restore the mask when the force value is left.

Open Force Process Variable (Ctrl+V) for the selected node. With a modern style, its grouped form scrolls while Close, Cancel, and Apply remain visible. Scroll down to reach the CALC expression and inputs.

The screenshot shows the repository's synthetic CALC example with Disable selected and an NE reset, rather than the literal-PV example above.

Use an expression

A calculated Force PV requires an expression. Inputs A–F can be constants or PV names:

GROUP NULL Facility
CHANNEL Facility example:pressure -----
$FORCEPV CALC -D--- 1 0
$FORCEPV_CALC A>0
$FORCEPV_CALC_A example:maintenance

Evaluation waits until all named PV inputs are available. Constants can evaluate immediately; omitted inputs are zero. The main-window footer shows the facility-wide count of disabled Force PVs.

Validate configuration changes before activating them. For argument limits and retry behavior, see the configuration reference and compatibility inventory.