I want to switch my RS-232 TX pin.For this I am using NPN transistor in between the TX line in such a way that the collector terminal is connected to controller side and Emitter to external side. The base is connected to a digital pin.
So, when the digital pin is high, the NPN transistor should close and TX line should send data from controller to external circuitry. But, in this case it was not sending data.
when I connect the serial line directly (without a NPN transistor), it was sending data properly.
I have also make sure that the NPN transistor is not faulty.
So, Why serial line is not switching by a transistor? Or is it not possible to switch a serial line like that?