How to know if a serial port is busy

Getting Started
1

Firstly: I’m using MacOS X

Now the problem: I know how to set up serial ports, including selection from a drop-down list, etc. But how can I detect if one or more of the serial ports reported by the system is already in use by another application?

thanks,
Richard

2

I believe if you attempt to open a port already in use, the system will give you an error. Pretty sure that’s the way it works in Windows.

3

It doesn’t seem to work that way on MacOS as far as I can tell.

thanks,
Richard

4

[quote=100319:@Richard Francis]Firstly: I’m using MacOS X

Now the problem: I know how to set up serial ports, including selection from a drop-down list, etc. But how can I detect if one or more of the serial ports reported by the system is already in use by another application?
[/quote]

Normally, opening a port will change DataCarrierDetect, maybe other hardware signal pins. You may want to use the code example from http://documentation.xojo.com/index.php/Serial.DataCarrierDetect to monitor the pins of a serial port, and open it from another application, to see what kind of change occurs.

For more about hardware signals see RS-232 - Wikipedia

PS : I cannot test this for you, I have stopped using RS-232 a long time ago :wink:

5

http://opensource.the-meiers.org/

have a look at the bottom of the page. there is a xojo serial port testing app thats quite good for learning stuff