Detect Power Failure

[koossa]

Will I use a Transistor to detect power on the USB Port?

[BobP]

Hi,

If you are going to use a seperate 5v supply say the 5v from the other PC I would strongly recommend using an optocoupler to monitor the 5v.

Bob

[koossa]

Thank you!!

[mister_e]

What happen to the USB power rail if someone reboot the computer or shut it down for a short period of time (if at all possible or allowed)?

In this case a simple wall-wart transformer would do the job too.

[koossa]

Mister_e

Would I still use the optocoupler if I rather want to use a transformer?

Thank you

Koossa

[mister_e]

No real need for an opto-coupler in that case.

[aratti]

it must send something to the PC via RS232 and the PC must send me an SMS or email.

koossa, The SMS IO Controller will do what you need sending via sms the status of the inputs every times there is a change. Download the project at this link:
http://techni.caliti.es/blog/2008/12...ontroller.html

and read the manual to see how to use it.

Al.