RS232 Software Support


INTRODUCTION
This page has been written to introduce a user to RS232 software support. This software support can be used to transfer data to any RS232 compliant devices.

BACKGROUND
Data transmission and support is essential for all information devices. This MTTTY program is an open source program proved by Microsoft which gives a good demonstartion on how to use RS232. It can be easily modified for a customized software program for your device.
C Code
To start off, you will want to compile and run MTTTY which is here. You will need any version of Microsoft Visual C++ to compile this program. You probably have Visual C++ already if a file called MTTTY.dsw looks like the icon below.
Connecting to Com Port
Connecting to the com port is very easy. First select the com port you want to use. Most computers only have 2 com ports, thus COM1 and COM2 will be the only valid choices. If invalid com ports are chose and error will be flagged as shown below.

Once a valid com port is selected, go to the File menu and select connect.
Configuration of Data Transmission Format
The following Table illustrates the main configurable features of the program.
Configuration
Item

Description
capable (V)
Buad Rate Set the transmission rate for the bits. Numbers are in bits/s. Note that the device connected to the PC that MTTTY is running on must have the same transmission rate.
Parity

 Parity is used for error checking. If error checking is a concern, parity should be enabled. See here for how Parity works in byte data transmission.
Data Bits The number of data bits to sent for each data payload. One can send a variaty number of bits in between a given start and stop bit. See references on how RS232 signal levels work.
Stop Bits This specifies the length of stop bits, which also specifies how close two successive data payloads. Stop bits are needed to indicate that the end of a data payload has occured. See references on how RS232 data packets are formatted.
Flow Control This specifies the type of handshaking signals used. It can vary from Hardware to Software. For example CTS is an active low signal specifing to MTTTY that it is Clear to Send. It is up to you to see how your device responds to these signals and when to send signal to the PC.


For more information please contact Andrew Ling.



Group Members:
 Darren Gonek
Guillermo Barreiro
Andrew Ling
Shyam Chadha
Timmy Li
Reid Orsten


Group AppNotes
TTL to Serial
DC Motor Control
CodeWarrior Tutorial
Surviving VI
RS232 Protocol
RS232 Software Support

References:
Maxim Semiconductor (Free samples of MAX232A IC)
RS232 Serial Port
MAX232A Spec Sheet