Stairwell Timer

The Stairwell Timer node manages a timed digital output.

When the Input connector receives the value 1, the node sends 1 to the Output connector and starts a timer.
When the configured time expires, the node sends 0 to the Output connector.

The node also provides retrigger, manual OFF, pre-warning, time override and remaining-time functions.

The Stairwell Timer is activated when:

Input = 1

At that moment:

• Output becomes 1;
• the timer starts;
• Time left begins representing the remaining activation time.

When the timer expires:

Output = 0

If the node is configured with a warning period, the Warning output becomes active shortly before the timer expires.

The Time for ON property defines the normal activation time.

Conceptually:

Input = 1 → Output = 1 for Time for ON

When this time has elapsed:

Output = 0

For example:

when the node is activated, the Output remains equal to 1 for 120 seconds.

When Retriggerable is enabled, the active timer can be restarted by receiving another activation command.

For example, assume:

Time for ON = 60 seconds

and the timer has 20 seconds remaining.

If the Input receives 1 again, the countdown restarts from the configured activation time.

Conceptually:

New Input = 1 → Timer restarts

When Retriggerable is disabled, a new activation command does not restart the timer while the current timing cycle is already active.

The Manual OFF property determines whether the Input can immediately switch the output OFF.

When Manual OFF is enabled:

• Input = 1 starts the timer and switches Output = 1;
• when Input returns to 0, Output immediately becomes 0;
• the active timer is stopped.

When Manual OFF is disabled:

• the transition of Input to 0 does not immediately switch the output OFF;
• Output remains active until the timer expires.

The Warning output provides an advance indication that the activation time is about to expire.

The warning interval is configured using:

Warning before OFF

When the remaining time reaches the configured warning interval, and Output is still equal to 1:

Warning = 1

This signal can be used to inform another logic function that the timed activation is close to ending.

Assume:

The sequence is:

• timer starts;
• Output remains 1;
• after 110 seconds, 10 seconds remain;
• Warning = 1;
• after another 10 seconds, the timer expires;
• Output = 0.

The ON time override input allows the normal activation duration to be changed.

Instead of always using the value defined by Time for ON, the node can use an alternative duration supplied through this connector.

This is useful when the same Stairwell Timer must operate with different timing values according to the current system condition.

Suppose the normal configuration is:

Time for ON = 60 seconds

but another logic provides an override value corresponding to a longer activation period.

The node can then use the overridden duration instead of the standard configured value.

This allows the timing to be adjusted dynamically without changing the node configuration.

The Time left output provides the remaining timer duration.

During the active countdown, this value decreases as the timer approaches expiration.

This output can be used for:

• displaying the remaining activation time;
• creating additional warning conditions;
• triggering other logic based on the remaining time;
• monitoring the timer during simulation.

Assume the following configuration:

When:

Input = 1

the node sets:

Output = 1

and starts a 60-second timer.

After 50 seconds:

Warning = 1

because only 10 seconds remain.

If another activation command is received before expiration and Retriggerable is enabled, the timer restarts.

If no new activation is received, after 60 seconds:

Output = 0

Assume:

Manual OFF = Enabled

and the timer is currently running.

If:

Input = 0

before the timer expires, the node immediately sets:

Output = 0

and stops the current timer.

Assume:

Time for ON = 90 seconds

The timer starts and 30 seconds remain.

If the Input receives 1 again and Retriggerable is enabled, the timer restarts from:

90 seconds

The output therefore remains active for a new complete timing period.

The Stairwell Timer is useful whenever a digital output must remain active for a limited period.

Typical applications include:

• stairwell lighting;
• corridor lighting;
• timed room lighting;
• temporary ventilation;
• delayed automatic switch-off;
• timed enable commands;
• warning before automatic deactivation.

The Stairwell Timer can be tested using the Logic Module simulation tools.

A typical test procedure is the following:

• configure Time for ON;
• configure Retriggerable;
• configure Manual OFF;
• configure Warning before OFF;
• connect a digital value to Input;
• start the simulation;
• set Input = 1 and verify that Output = 1;
• monitor Time left;
• verify that Warning becomes 1 at the configured interval before expiration;
• wait for the timer to expire and verify that Output = 0;
• enable Retriggerable, activate the timer again and send another value 1 before expiration;
• verify that the timer restarts;
• enable Manual OFF, activate the timer and then set Input = 0;
• verify that the Output immediately becomes 0;
• test ON time override with a different activation duration.

• Time for ON defines the standard activation duration.
• Retriggerable restarts the countdown when a new activation value is received.
• Manual OFF allows the Input to stop the timer immediately when it returns to 0.
• Warning before OFF defines when the Warning output is activated before expiration.
• ON time override can be used to dynamically change the activation time.
• Time left provides the current remaining timer value.
• Make sure that the warning time is appropriate for the configured ON time.

• Logic Module
• Logic Module - Simulation management