Hello,

I want to control a program written in VB through a USB port on a PC. The idea is this. Currently a function in my program is activated by pressing a software button on the GUI. I want to use a switch (a push button) connected one of the USB ports instead for this function. I have a Serial to USB adapter cable. I believe I should be able to connect a push button switch to RS232 end to change the state of the receive pin so that OnComm event of the Serial control is activated. So if I pool receive buffer continuously I should be able to detect the data (high or low?) and initiate my function. But I do know how to do the electronics. Where should I connect the switch? There are three important pins on the serial end of the adapter: 2: Receive, 3:Transmit, and 5: Ground. Do I need to power the one end of the switch with 5V? How long do I need to press the switch?

There might be simple USB switches that do what I need. I am open to any suggestions. I just need to have a very simple and small circuit without any extra power other than the 5V supplied by the computer through the USB port.

Thank you

 

if you connect switch between pins 2 and 3 you can send data to serial port. if anything comes back switch is closed. if nothing comes back, switch is open.