Hi,

I'm having a problem with a 5V 20mA led that is wired to two different I/O cards the I/O card A and I/O card B. I want to use the card A and the card B each at a time not both at the same time. So when the card A is connected to the computer and powered the card B is unplugged and vice versa.
What happens is that if the wires that goes from the led to the card B are connected to the card the led does not light. As soon as I remove them from the card the light comes on. The card B is unplugged .
What is causing this. Could you please help?

Best Regards
Abrupto

 

could you attach a circuit diagram to help us understand wat u mean i dont actually get wat u mean

 

could you attach a circuit diagram to help us understand wat u mean i dont actually get wat u mean

Tank you for your help. Sorry about my drawing... I'm a newbie...

Regards
Abrupto

 

where is the led connected in the card ???

 

both cards have predifined places to wire the the leds. They are wired there.
Regards

 

i mean u sure u connected the ground to the -ve and the vcc to the +ve or did u invert it

 

Tank you
I'm sure the connections are correct. Double check twice

 

when do u want the led to light exactly ?

 

as soon as the switch is turned to the on position

 

wat switches there are no switches in the schematic u drew