Timeout Filter

After the first value has been sent, if no subsequent value is published within the specified timeout period, send a templatable value which defaults to NaN. The value may also be set to last, which will result in the last value received by the filter being sent again.

This filter particularly is useful when:

data is derived from some communication channel (a serial port, for example) which can potentially be interrupted.
placed ahead of a throttle filter to ensure that the last value published will pass through the throttle.

# Example configuration entry
filters:
  - timeout: 10s  # sent value will be NaN
  - timeout:
      timeout: 10s
      value: !lambda return 0;
  - timeout:
      timeout: 10s
      value: last  # sent value will be the last value received by the filter