ModBus RS-485 TTL device needed?

I would like to use a spare Core I have to drop a wireless RS485 “snooper” on a device I have outside. I have read the threads that reference RS485 and have the library @peekay123 ported but what is unclear to me is if I need a RS485 to TTL device like the one below or if I can just wire in from my RS485 device and read directly. Also the referenced TTL to RS485 device appears to support 3.3v logic but is the only one. Can I use a 5v device as long as I tie it to 5v tolerant pins? Long term I want to do more than snoop, I would like to be able to issue commands via the Core to my RS485 device, does that change anything?