Register lag when accessing Stiebel Eltron Heat Pump via HA Modbus Integration

Started to play around with the HA Modbus integration to read data from my Stiebel Eltron Heat Pump. The example is as easy as it can be:

modbus:
  - name: stiebel_eltron_hub
    type: tcp
    host: 192.168.x.x
    port: 502
    sensors:
      - name: se_aussentemperatur
        unit_of_measurement: °C
        slave: 1
        scale: 0.1
        input_type: input
        address: 506
      - name: se_wwisttemperatur
        unit_of_measurement: °C
        slave: 1
        scale: 0.1
        input_type: input
        address: 521

Everything work as expected but what I’m observing consistently is a register lag by 1. I.e. If I want to read Modbus register 507 I have to use address: 506. This is confirmed by e.g. qModMaster where I get the value of register 507 when requesting 507.

Is there any parameter in the Modbus Integration I missed out which might cause the register lag?

Thanks for your comments and ideas!
Tiro

MODBUS starts counting at 0 while documentation starts with 1.
Not aware that you can change this in the configuration