Modbus switch mod:16

my PLC accept write mod:16
the modbus switch standard is not work

switch:
  platform: modbus
  registers:
    - name: mod_Register1
      hub: RS485
      slave: 1
      register: 399
      command_on: "1"
      command_off: "1"

instead in develop>service
with modbus.write_register

unit: 1
value: [1]
hub: RS485
address: 399

prefectly work

how to edit the custom_component modbus switch.py file to accept the array [1] ?