Read serial port data using Digital I/O

[score99]

I have a seial port peripheral which streams asynchronously (pin 2) with 9600/8/n/1. Instead of using hyperterminal to read the data, I would like to read it using my 6024E DAQboard's digital I/O line. I can't figure out how to time them or how to detect the start and stop bits. I am trying to do all this because I have a second device which has analog output and I am already aquiring that data using the DAQboard, so it is easier to sync data aquisition if I use the same board for digital and analog input, instead of trying to sync the RS232 port to the DAQboard. Greatly appreciate all help.

[ScottieB]

Hello,

It may be rather involved to detect the start bit/stop bit and data bits in a serial transmission. You're basically going to be designing your own UART (serial communication chip). Remember that the levels of RS232 serial communications are usually -10V to +10V rather than the TTL (0V to 5V or so) levels that your digital I/O line. Refer to the following external site for lots of information about the RS232 protocol. If you could give me more information about your application, perhaps there is an easier way to implement what you are trying to do.

Serial information: www.lvr.com

Scott B.
Applications Engineer
National Instruments