On/Off Light and read status with Modbus RTU

[cusna]

Hi all,
this is my first post and I hope to write in the right place.
Start now to use Domoticz installed on Raspberry.
I have a of experience regarding hardware and also MODBUS protocol, having designed and built several boards (with implemented modbus rtu).
For this I would like to use my hardware to activate home light.
L'impianto di casa attualmente ha pulsanti che agiscono su rele passo passo, questi pulsanti li vorrei mantenere per utilizzo anche manuale.
Then connect a modbus relay board (485) with the NO contacts of the on-board relays that act as manual pushbuttons, closing the contact for 1 second and then releasing it).
This is managed by a proper programming of my SLAVE, with Domoticz I only have to write a value in a register.
I use the plugin viewtopic.php?t=21297 (modbus-write) and up to here it works.
Now with the other plugin (modbus-read) I would like to read the status of other registers to see if the lights are on (thinks my hardware to set appropriate registers when the light is actually on, even by the manual buttons).
I do not know how to do graphically, that is, display an icna light bulb in which you can press to send a write command (modbus-write) and at the same time that the light bulb changes status using the reading (modbus-read) of another register , in order to have in real time if turned on or off
Thank you in advance