Ok, here is the formatted code for switching on the siren:
zet_heiman_sirene_aan:
alias: zet_heiman_sirene_aan
sequence:
- service: mqtt.publish
data:
qos: '1'
retain: false
topic: zigbee2mqtt/Heiman sirene/set
payload: '{"warning": {"mode": "burglar", "level": "very_high", "strobe_level":
"high", "strobe": "true", "strobe_duty_cycle": 10, "duration": 1800}}'
mode: single
icon: mdi:alarm-light
and here for switching it off:
zet_heiman_sirene_uit_2:
alias: zet_heiman_sirene_uit_2
sequence:
- service: mqtt.publish
data:
qos: '1'
retain: false
topic: zigbee2mqtt/Heiman sirene/set
payload: '{"warning": {"mode": "stop"}}'
mode: single
icon: mdi:alarm-light-off