Detect voltage change and send an email

fabriziojoe

Active Member
I have a new project that I want to tackle and I am not sure what components to use.
I have a new hd enclosure that has an LED light on the front (blue=everything ok, red=failure).
When the led changes to red I would like to send an email.

I figured I could monitor the voltage for the red leg of the led (usually +5volts?)

This seems pretty simple, but I have never tackled anything like this before.

Any help would be greatly appreciated.

Thanks!
 
The voltage across the LED is going to be around 1.5V. If you could locate the resistor in series it is probably 3.3V or possibly 5V. Since you don't know if the LED is referenced to ground or some other voltage it is best to isolate the signal. You can use a photodiode over the LED and measure the output so you can distinguish between green and red. Or you can wire an opto coupler to the LED but current sharing between the LED and optocoupler LED may be an issue. Once you get an isolated signal the next step is to generate the email. Depending on the hardware you may already have you have a few options. One way would be the Webcontrol board:

http://www.cocoontech.com/forums/index.php?showtopic=15005

I haven't used one but it looks like it will do what you want.
 
I can recommend CAI WebControl for this. It has 3 analog inputs. You can use one of them to monitor your red LED. Through browser, you can see the voltage of the red LED. For example 1V will read 100. Then paste a simple PLC code into it:
START
TSTGE A1 100
EMAIL EM1
DELAY 1000
END

This will check the red LED once every second.
 
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