Delay Gate

Is node-red node that can be used to pass messages only after certain delay period since the initial "trigger message" has passed.

After the initial delay the gate can either stay open until the closing timer expires or be closed immediately after the first message is forwarded.

Valid message

Unless specified, all input messages to the node are considered valid. Optionally you can make the node react to only messages with specific msg.payload value and type. Payload type and value can be specified in node properties. When payload value has been configured in node settings all other messages are considered invalid.

Behaviour

The node has three states:

• closed state
• delay state
• open state

Initially the node is in closed state.

When the first valid message is received the node enters delay state and starts delay timer. During the delay state all valid messages are ignored. When invalid message is received during the delay state the delay is cancelled and the node returns to closed state.

When the delay period has passed the node enters open state and the next valid message will be passed to gate output.

In case the node is configured to close the gate immediately after passing the message the gate returns to closed state after passing the first message. Otherwise it stays open for valid messages until the gate open period has passed. In case invalid message is received during that time the gate returns to closed state immediately.

Practical example

Let's say you have a movement sensor in a room and you want to switch on an appliance, for example a ventilator, when the movement is detected. However you want to do that only after somebody moves in a room for a longer period of time so occasional short movement in a room would not switch on the appliance.