Modbus register not updating immediately

ESPHome
1

Hey.
I’m trying to control my Nilan heatpump.
I’ve set up a “select” for updating the month-time, but it seems that the value isn’t written to the controller immediately, but only at a set interval (I think 30 secs).
If I navigate away from the selector within that time, the change isn’t written.
Is there any way to make sure the value is written to the register immediately?

Here’s the code:

select:

  - platform: modbus_controller
    modbus_controller_id: nilan_modbus_controller
    name: "Select Month"
    id: nilan_month_selector
    address: 304
    force_new_range: true
    use_write_multiple: true
    optimistic: true
    value_type: U_WORD
    optionsmap:
      "January": 0
      "February": 1
      "March": 2
      "April": 3
      "May": 4
      "June": 5
      "July": 6
      "August": 7
      "September": 8
      "October": 9
      "November": 10
      "December": 11

and here’s the modbus setup part:

uart:
  rx_pin: GPIO16
  tx_pin: GPIO17
  parity: EVEN
  baud_rate: 19200
  id: uart_modbus
  stop_bits: 1

modbus:
  id: modbus_id
  #flow_control_pin: 26
  uart_id: uart_modbus

modbus_controller:
  id: nilan_modbus_controller
  address: 30
  modbus_id: modbus_id