I would like to use the interface on link below. I tried to do exactly same except output because to test first, I gave output to LED from microcontroller.
My question is with MC1489. When i connected 5V to VCC, I always get continous signal from 3rd pin (1Y on datasheet.) It doesn't matter if I connect 24V input to pin (1A) or not.
How should I connect it exactly to control over output pin? What does the control pin do? In the interface schematic there is no connection to the control pin. Should it float or what should I connect there?