Usb to serial rs 485 ACPi adapter

[OLopezNYC]

I am currently working on a USB TO Serial converter. please look at schematic enclosed of the RS232 to 485 converter that I am using currently. My question is, can I make this cable USB instead of db9 serial. The Cable is used to interface with Elevator PLC controllers but my issue is that those cables are not usb. Is there any way I can do this?

The second image shows the configuration another configuration that also works for us using a B&B 485CON Converter. I can not make it work with USB to serial converter because I need to set the port to ACPI Communications at my device manager port driver settings. I hope I'm in the right place for this kind of stuff.

[somlioy]

Could this (page 27) be something?

[mikeselectricstuff]

Why reinvent the wheel - there are plenty of perfectly good USB-485 adapters out there (and a few rubbish ones)
Easysync do a good range : http://www.easysync-ltd.com/category/145/usb-to-rs485.html