I am using Rs232 to TTL module to get data from some device. And then this module will pass the data to Arduino. However, the module does not pass any data to Arduino (The transmit led not blink all the time).
Can anyone give me some hints to solve it?
This is the wiring diagram..
Which module?
It is not clear that you are making the right connections. Is the "RS232 device" supposed to be transmitting or receiving? If transmitting, it should output data on pin 3 of the DB9 connector.
Study the connections for this module as an example: Pololu 23201a Serial Adapter Fully Assembled