Thank you for sharing Barry, this is actually the approach I am going to try (with a SILEX DS-600 USB host instead of a raspberry pi, and a 1747-UIC Cable). Ken and company had some luck with it in the thread he linked above.
James, thanks for the link. I had not heard of SantaClara Systems but they do have some unique products and resources on their site. Doesn't look like they play in the DH485 space but a good resource to have for later.
Thanks for the help everyone, I will let you all know how it goes with the USB host route.
Programming was a bit slow (~70KB ladder took probably 2 minutes to flash over) but worked! I was worried about latency because my network is non-trivial (There are at least 2 managed switches and 1 unmanaged switch between my VM hardware and the SLC5/03). While it was slower than my testbench (unmanaged Gig-E switch), RSLinx driver diagnostics did not indicate any dropped packets.
I'll be running this for a while just monitoring so I will check in with the engineer after a bit and see how his consistent it is for monitoring.
Thanks everyone who suggested a Ethernet USB device host. One thing of note - I tried the usb 3.0 port on my device host first and it didn't work right, switching to the usb 2.0 port fixed it. Silex makes the same hardware but with Wifi compatibility that I am tempted to try, may make a new thread for that.
I attached a screenshot of my RSLinx settings just in case anyone wants to replicate. This was for the SLC5/03 default config, may be different for you if you have a different channel config. I did not have to change any settings on the Silex unit. I had to switch the UIC to RS485 with the hardware switch on the side.
