Modbus-TCP "authorization"

[Виталий Балакин via Tech-talk <tech-talk@aps.anl.gov>]

Hi!

I have a Modbus-TCP device which requires a so called "authorization" to
be performed BEFORE any actual I/O can take place; without such an
authorization all register writes and even reads result in exception 2
("illegal data address").

The "authorization" consists of several register reads and writes, in
specific order:

   1. Write INT32_LE:0x89ABCDEF to holding registers 0x2100,0x2101
   2. Write INT32_LE:0x01234567 to holding registers 0x2102,0x2103
   3. Write 0 to holding register 0x2104
   4. Read discrete input 0x2200

Is there some mechanism to perform this sequence immediately upon connect?
Looking at "modbus" module documentation, I see nothing relevant.

Thanks in advance!

Vitalii