LED Pin on 6001 not lighting up

[BertMcMahan · Accepted solution]

The line "For applications that use the LED signal, connect a 4.7 kOhm resistor from the LED signal to the +5V signal." is ambiguous to me.

Do they mean "For applications that need to light up an LED?" or do they mean "For applications that need to measure the line as a digital signal"?

I wouldn't have thought to make the distinction after just reading the 6009 datasheet, but the 6001 has those two options explicitly broken out:

All that said... at the end of the day, it doesn't work as a direct driver, so you probably need to connect it between 5V and the LED signal. I know you're using the 5V line for something else, but if it works then I'd split it off and use it for both. A tiny LED shouldn't increase the current draw by much at all, so I doubt you'd pull too much current (though you should probably look it up just to be safe).

[Sid05]

Yes there is ambiguity. I really benefited from the 6009 LED status indicator wrt the GND, since every now and then the 6009 would get suspended and the LED would stop blinking at that point of time indicating that suspension. Then I had to power reset or reset via NI Max. Later I realized it was likely due to the use of a USB-hub. Now I have gotten away from that approach. 

Let me check that piece out of splitting the 5V from the 6001 and power that LED and the 5V relay board. That is what I was wondering about too. I see that the 5V LEDs typically draw 20 mA and the 5V relay board ~70 mA. The 6001 outputs 150 mA I recall. So, may be that will work. 

Will let you know. Thanks.  

[Henrik_Volkers]

a recent high efficient (red or green) LED will have a clear visible optical signal with less than 1 mA.

If you use 4.7KOhm as a current limiting resistor the resulting current will be about 0.6 mA .

(5V_supply - 1.8V_LED - (0.5?) V_transistor) / 4700R_limit

Just give it a try 😄

[Sid05]

Thanks all - yes it works in this configuration, i.e. when I split up the 5V from the 6001 to power both the LED and the relay board, with reference to LED Status Pin and Ground pins respectively.