Stepping MQTT cover slider on arrows actio

Hello all,

I’m rather new to home Assistant and yaml stuff, so please be kind (and I’m not native english speaking neither).

I’m operating King Q4 covers using tasmota over MQTT on a PS-16-DZ module configutation. It does the job more or less, unless the synchronization of the slider with the on/off commands. The slider has effetc on the staus open/closed, but the action to open or close doesn’t affect the slider at all.

Not ready to dive in the driver code, I’d like to have a dimmer action from home assistant in parallel with the open/close actions but I do not even find how to try that.

For instance, the action below:
payload_open: 'AT+UPDATE="sequence":"1576774195000","switch":"on"'

would also run an increment from 0 to 100 by steps of 5 every 5 seconds.

Any idea how I can do this ?

As info, the full configuration for each cover is like below:

cover Volet_Cheminee:
    platform: mqtt
    name: "volet cheminée"
    device_class: shade
    availability_topic: "tele/volet_cheminee/LWT"
    payload_available: "Connecté"
    payload_not_available: "Déconnecté"
    position_topic: "stat/volet_cheminee/position"
    position_open: 100
    position_closed: 0
    set_position_topic: "cmnd/volet_cheminee/Dimmer"
    command_topic: "cmnd/volet_cheminee/SerialSend2"
    payload_open: 'AT+UPDATE="sequence":"1576774195000","switch":"on"'
    payload_close: 'AT+UPDATE="sequence":"1576774195000","switch":"off"'
    payload_stop: 'AT+UPDATE="sequence":"1576774195000","switch":"pause"'
    retain: true
    optimistic: false
    qos: 1