I have to connect PIR sensor HC-SR01 to Arduino using RS485 such that PIR sensor's TTL signal gets converted to RS485 while transfer and gets converted back to TTL while receiving on Arduino side. Since my circuit is not working as expected I replaced Arduino with a LED for testing. Can any let me know what is wrong with below circuit? my LED gets on for few seconds as soon as I give power and goes off after that indefinitely. Ideally it should be on and off when there is a motion in front of PIR sensor.
the data sheet for pir sensor is https://www.mpja.com/download/31227sc.pdf
my objective is
----> TTL ----> RS485 transmitter ---------> Long Cable-------> RS485 Receiver -----> Arduino