PCIe-6321 to control a relay

[FabriceMTL]

Hi y'all,

Currently we are using an arduino in conjunction with our DAQ (NI USB-6211 OEM) to control a relay (http://www.digikey.ca/product-search/en?keywords=4-1393117-8). The way we implement it is like this :

Initiate a digital output pin to HIGH as power-up state, in the Arduino have a code that will read this pin and detect when it's low (when the DAQ shut off or restart) and then the arduino will change one off it's pin connected to a transistor (http://www.digikey.ca/product-detail/en/2N7000/2N7000FS-ND/244278) to HIGH so that the the transistor switch the relay ON or OFF.

The problem with this implementation is 1) when updating drivers and stuff USB related the arduino detect the LOW (DAQ restart maybe) on the pin and shutdown the instrument and 2) Due to USB mysterious behavior sometime the Arduino still detect LOW...

To correct this we decided to go with the PCIe -6321 and ditch the USB DAQ for an improved reliability and now I want to get rid of the Arduino (it was used for other purpose before but now it just handle the power off of the instrument). So my question is can I just connect directly a digital output of the PCIe DAQ to the transistor and manage the state of this port in software ? (Start PC = Power-up state = Low; Launch application = turn DO to HIGH = Start the instrument; Close application = turn DO to LOW = Shutdown the instrument)

i.e. Picture attached

According to the spec the DIO pins of the arduino can provide 20mA while the PCIe-6321 provide 24mA Maximum. I am also using a power supply for the relay. So do you think it will work like that?

[crossrulz]

If the DAQ can put out as much current as the Arduino, I see no reason you couldn't use the same circuit that the Arduino used.  I would not use a direct connect to a relay.