Multimodem

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Ramón
New member
Username: El_miche

Post Number: 15
Registered: 02-2008
Posted on Friday, January 15, 2010 - 04:31 pm:   

Hi Des,

I am try to build a gateway whit multiple USB modems (all Option Icon 225)

I tested two diferent machines whit two diferent OS each one:

Machine A) WinXP SP3: is restarted when third modem is conected.
Machine B) Win2K Pro SP4: only one stick is recognized like a modem.

could you recommend on your experience, what OS is suitable for this purpose (I am thinking use ten or more modems). Can I have problems with hardware (motherboard or USB controller)?

Best Regards.

Juan Ramón
Des - NowSMS Support
Board Administrator
Username: Desosms

Post Number: 1661
Registered: 08-2008
Posted on Tuesday, January 19, 2010 - 05:02 pm:   

Hi Juan Ramón,

This type of issue can be difficult to troubleshoot, as the problem could be different areas.

1.) It could be a USB driver issue. Some USB modem drivers are not designed to handle more than one of the same modem simultaneously. I've installed multiple Option ICON 322 modems without a problem, so I'd expect the 225 model to also be ok, but this could be a problem.

Installing different modems from different manufacturers can work around problems with drivers that do not allow multiple modems.

2.) The operating system could also be an issue. I don't think there are any multiple device limitations in XP, but it is not surprising that 2K will not recognise more than one of the same device.

3.) USB hub power usage is the most likely culprit if your computer is restarting. Most USB modems draw 500 mA, which I believe is the max power draw per port supported in the USB standard.

Your USB root hub needs to be able to supply enough power for all of the USB devices that are connected. It sounds to me like when you are connecting that 3rd modem, it is overloading the USB hub leading to a crash.

Here are some links to information about USB power usage that may help.

http://www.google.com/search?q=check+usb+power+usage

--
Des
NowSMS Support