Question:
In an RS-485 network, what happens if I connect a MAX3486 device which is switched off (powered off)? Does it hold the bus, or it is possible for other transceivers to communicate over the bus?
Answer:
When the MAX3486 is not powered, the bus loading is simply the integrated receiver input termination resistance of 12kΩ minimum (single unit load), which is always present whether the transceiver is powered or not. In theory, you could have up to 32 single unit load devices connected to the bus, and not powered, and active devices can still communicate on the bus. This is not mentioned in the datasheet because this is the standard specification for RS-485.