vfs11 cable interface

Hi All,
I have a TOSHIBA VF-S11S 2007 PL-WP 0.75kW and I would to switch from 0-10V to modbus and serial cable using linuxcnc vfs11 VFD driver (www.linuxcnc.org/docs/html/drivers/VFS11.html).


Looking the original schema (git.mah.priv.at/gitweb/vfs11-vfd.git/blo...rod:/vfs11-rs232.pdf) , the 74hct14n are inverting, this mean that vfs11 uses inverted signal as rs232 but translated to 5V ttl level.
My idea is to switch from rs-232/max232 to a FTDI FT232RL USB to serial and inverting signal using the 74hct14n.

Someone can share his experience and/or advice?

Interface described here git.mah.priv.at/gitweb/vfs11-vfd.git/blo...rod:/vfs11-rs232.pdf could be equivalent to a rs-232 to rs-422 interface where are used only RX+ and TX+ relative to gorund?
The voltage divider in the schema step down just at 90% the tx line from vfd, how much can it be necessary?

I mean RX- and TX- should be the same signal inverted by the 74hct14n next to the max232.