node-red-contrib-error-on-timeout

Node red contribution node that triggers an error if a second message has not been received within a configurable timeframe.

Usage

This node receives at first a message with the eot_trigger property set and then starts the delay until a message with the eot_input flag arrives.

Warning

This node is not suitable for high frequency message processing. It is meant to help control the flow by checking a command / acknowledgement pattern such as switching equipment on and off. See my use case.

Dead lock

Once the node receives a message with the eot_trigger flag set, it'll be waiting for a message with the eot_input flag and won't accept any more trigger messages untile the configured timeout has been triggered.

Outputs

1. Success output: All messages that have arrived within the configured timeframe
2. Error output: When no message arrives within the configured timeframe
3. Late output: All messages that arrived after the configured timeframe

Programmatic configuration of the timeout interval

The message with the eot_trigger property can have a eot_timeout property set to the desired interval in milliseconds.

Latency stats

The following properties/fields are added to the messages coming out of each individual output of the node:

| Output | Fields | |--- |--- | | Success | eot_timeout Configured timeout in millisecondseot_time Time in milliseconds it took until the expected message arrived | | Error | topic is set to error-on-timeoutpayload Formatted error message reading Input message not received within ${timeout} mseot_trigger A copy of the message that triggered the timer that resulted in the timeout | | Late | eot_timeout Configured timeout in millisecondseot_time Time in milliseconds it took until the late message arrivedeot_late Late time in milliseconds |

My use case

I'm working on an IoT project running on MQTT where successfull execution of commands is crucial. After sending a command to a device I needed to ensure that the command has been executed successfully by having the device send out an ack message within a certain timeframe before turning on other heavy duty equipment (and potentially blow up the entire infrastructure).

sequenceDiagram
    Actor Node Red
    Actor Selenoid
    Actor Pump
    Node Red->>Selenoid: Open
    Selenoid->>Node Red: ACK
    Node Red->>Pump: Run
    Pump->>Node Red: ACK

The default nodes that come with Node Red seemed to be too... redundant for my needs and I preferred to develop something simple and concise and wrap it into a node.

I sincerely do hope that you make good use of it.

Please see the examples by importing them through the Import > Examples dialog.