Comm port communication between modem and computer

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Antonio_Magma

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Comm port communication

I have a modem which i have built myself and i want to link to computers together through the modems. The modem is connected to the computers through the comm port.

Only pin2 (recieve), pin3 (transmit) and pin5 (ground) are used. I have used VB6 to create an instant messenger but the 2 computers can't recieve message from each other. How do i test whether or not my modems are communicating through the ports without using the messenger or other software? The 2 computers are running with Windows 95.

Thanks guys.
 

Re: Comm port communication

You have to check some things:
1 - Both serials are configurate as same form?
1 - Your program is writing on serial port? You just will know this with an oscilloscope.
2 - The cable is an crossover, eg. the pin RX1 is on TX2 and RX2 is on TX1.
3 - The distance between the computers is big? This cable is together with power cables.
4 - You can use a serial port watch, or hyper terminal; to see if has any sinal arriving on another computer .....
5 - Probaly you have an owner protocol to comunicate, maybe your software see a CRC error... etc, if you send more information, what tests do you do yet?

I will send a port watch that I do, for tests. This program works well, but works only with 8 bits, no parity, one stop bit.
 

Re: Comm port communication

Thx leomecma...

apparently it works when i connect pin2 to pin3 with the PC1 to the master modem...and pin2 to pin2 with the PC2 to the slave modem....
 

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