How to access RS485 on Mesa 7i96?

I was watching a video on YouTube where a USB RS485 device was used to control a VFD spindle. I was wondering if it is possible to do this using the RS485 port on the Mesa 7i96 instead of having to use an extra USB device.

Here is the code that was used to access the USB device. Is it even possible to do this with the Mesa 7i96? If so what would I change?

loadusr -Wn vfd hy_vfd -n vfd -d /dev/ttyUSB0 -p none -r 9600

net spindle-cmd-rpm-abs => vfd.speed-command
net spindle-cw motion.spindle-forward =. vfd.spindle-forward
net spindle-ccw motion.spindle-reverse => vfd.spindle-reverse
net on motion.spindle-on => vfd.spindle-on

Unfortunately this is not doable yet

Yes, hoping at some point that a string hal type would allow decoupling
the low level driver from the formatter component (modbus etc)

In several FAQ plenty oft people asking to connect
Mesa cards via the rs422 to a vfd. Wouldn't it be possible to add a second rs 485 in future releases oft the cards?

Its probably possible but I think a cleaner way would be to support a hal string type
so this can all be done by a generic hal protocol component connected to the hal pins
exported by the UART TX and RX modules. This avoids losing real time if its desired
(and even if modbus for example is not real time, there's no reason to add userland
uncertainly to transactions)