I am using MAX485 chip for serial communication. But a weird behavior I found which I can not explain. Can any one help me in understanding why LED is ON in Receiver pin (RO) when I have not given any serial data from pin A and B? As per my understating LED should be always OFF as there is no data connection.
In above circuit, I have just switched on my MAX485 board by connecting source on Vcc and GND no data pins A and B are connected. And RE is connected with GND to turn board in receiver mode. So ideally RO should always be off due to no data.