flipdot 7seg from Alfazeta - send a frame to controler with RS485

Hello,

well, i bought a 7seg display with a controler from alfazeta (flipdot techno) and try to send datas to it...
7seg use RS485 and a "secret" protocol (frame look like modbus)

they've gave me a windows app to test display, it works...
but when i try to send datas to it with an arduino + rs485 module... nothing!
so to simplify i've tried to send a frame from a serial tools via the usb-rs485 (that work with alfazeta app)
and it work
i have for example to send a frame like this in hexa:
"80 89 00 34 8F"...

i use the lib rs485_protocol.h

on this forum there is an example code

when i try it (configure correctly the software serial and enable pin...)
nothing

i think i do not understand how to setup my message...

i assemble my message like this

byte msg [] = { 
       0x80,    // start byte
       0x89, // send byte and refresh
       0x00, // to all adress
       data[compteur%7],
       0x8F // end byte
    };

am i good or not.

thanks for your help

eric