Test RS232 TxD RxD

Hello,

How to do a test to a RS232 serial port so that it can assess the functioning of the lines TxD and RxD using using for example a pic12f675 or pic16f628.

Thanks

With the 16F628, you have two choices,
1. using the hardware USART with HSERIN/HSEROUT with the following schematic (Courtesy of Bruce)
http://www.rentron.com/images/004LOAD.GIF
2. Using any other bit banged solution like DEBUG/SEROUT/SEROUT2 without the MAX232, but only with a single resistor in serie (1.5K is fine) and set the Inverted Mode

For the 12F675, well, one choice... option 2 above.

Do a search here and you'll find tons of example.