NPN leak sensor to DIO

[nasu]

I have a Netmotion liquid leak optical sensor which uses a NPN transistor. I would like to connect it to the DI of a USB-6009 for labview to sense a liquid spill. Here is a link to the product page, I have model HPQ-D11-L05:

http://www.netmotion.com/htm_files/fh_leak.htm#one

It says that the output has a load current of 50 mA max, does this mean i just need to put a resistor in the circuit to convert to a 0 - 5 V signal or is there something else I need to do in order to detect an change in output.

Thanks

[K C]

Hi,

You can use a resistor (1k) but you have to connect the resistor to the +5V of the  USB-6009. Do not connect it to the power supply for your device (>12V).

Kees

[nasu]

Thanks, could you be a little more specific on how my wiring needs to be done. Do I connect the resistor between the black wire and +5V then measure the voltage accross the resistor for the TTL signal?

[K C]

You can connect it like this. The input is inverted. So an inactive output will show a '1'.

[nasu]

Tried and worked. Thanks so much for your help!

[K C]

Glad to help.

Kees