using 3G modem from desktop application

[alzomor]

Hi

I am trying to use a 3G modem from my application.
When I connect the 3G modem I notice 3 new ports on hyper terminal
My Question
Why 3 ports? and which one i should use ?

Regards
Hossam Alzomor

 

[horace1]

what is the make and model of the modem?

 

[alzomor]

Manufacturer: huawei
Model: K3770
Revision: 21.023.04.00.11

 

[ftsolutions]

Windows (pick your flavor) enumerates COM devices to a different COM port each time you plug a device (even the same device) into a USB port - if you have plugged it in to different USB ports those enumerations will persist. Go to the the Control panel System page and look in the HW manager, or on the Ports page to see the ports and click on them to get the manufacturer info, etc. if required to identify it and where it current is.

 

[throwaway18]

The three ports are usually "modem", "3G Application Interface", "3G PC UI Interface"
Some older 3G cards have two ports for modem and application interface.

I think it is so that the software can read signal strength etc while the modem port is being used for internet data.

Use whichever port works for your application. Modem port may respond to AT commands to send a text message etc.
You can try connecting to the port with hyperterminal, if you type ATZ modem port will respond OK.

You may have to stop the software supplied with the modem to be able to open the COM ports, only one program at a time can have a com port open.