Multiple Serial connections?


Licensed User
Is it possible to use two serial connections simultaniously?

I am working on some software which leverages a built in GPS on COM5 and a Vector device (RS232) on COM1. My device is an ASUS A639 with built in GPS.

I've added the serial components and created two serial objects serial1 and serial2.

At startup of the app, serial1 is new2'd and Opened on COM5 and works great.

When the user decides to connect to the Vector device, Serial2 is new2'd and Opened on COM1... or actually it's not. My "error opening port" message box is coming up and the port isn't opened.

If the user disconnects from the GPS on COM5, then attempts to connect to the device on COM1, it works fine and the data transfer is successful.

I just ran a test with a small app I wrote... It seems it may be a hardware issue.
I'm using an ASUS A639 PPC running WM6.

I can connect to any other COM port in the device sumultaniously with COM5 (GPS) except COM1.
Is it possible that ASUS wired the GPS to the serial port driver since they do not expose that serial port to the user?
To Use the COM1 port I cut up an extra sync cable, and experimented to find the Data Rx and Data Tx pins.

Is it possible this is just due to some settings I can change within the OS?


Thanks for any help anyone can offer,
Last edited:


Licensed User
Simultaneous Com Ports

Hi Chris,

You should not have problems using two serial ports simultaneously; I've done it with an HTC. But I don't know how is physically the COM1 you use in your ASUS, or what connector does it uses.

I suggest you to just try to only open, and send/receive data to/from your COM1, to see it it's available, and after that, add the GPS COM port.