Latch Timer Node for Node-RED

Author: Harshad Joshi (GitHub: hj91)

Overview

The Latch Timer Node for Node-RED is a custom node that acts as a timer with a latch functionality. The node takes a boolean input (true or false) or a 'reset' command. Depending on the input, it initiates a timer or resets the timer to its default state.

Use Cases

This node is particularly useful in scenarios where you want to hold a certain state (true or false) for a predefined time duration, such as:

- Turning on a device for a set amount of time.
- Simulating pulses in time-based control systems.
- Holding a state for a specified duration in state-machine implementations.

Functionality

The Latch Timer Node operates based on the input message payload:

- If the payload is true, the node initiates a timer for the duration set by the user in the node configuration. The output of the node during this time is true. After the timer duration has elapsed, the output is reset to false.
- If the payload is false, the output of the node is set to false. No timer is initiated in this case.
- If the payload is 'reset', the timer (if running) is immediately reset, and the output is set to false.

The node displays the current status under the node in the flow editor:

- "timer running" (green): The timer has been initiated and is currently running.
- "timer reset" (red): The timer has been reset and is not running.
- "timer completed" (blue): The timer has completed its run.

Installation

You can install this node directly from the Node-RED interface by searching for "latch-timer" in the palette, or manually using npm