How common is full duplex RS485 and RS422?

I’m designing an RS485 transceiver device and I’m wondering if I should include full duplex support. I see it on quite a few things, but I’m not sure how often it’s actually implemented.

I don’t want to be cutting out a large chunk of potential customers by not adding it.

What protocol is RS-485 handling? If the protocol expects full duplex, then you need to implement provision for full duplex, but that is more on the application level data handling side, than on the hardware bus side. Modbus RTU is a half duplex protocol; master polls, only the addressed slave replies. A Master can not talk to another master so there’s no reason for full duplex. Most Modbus slaves don’t have enough processing power to handle receiving one message while simultaneously sending another.