Does PXI 6514 need a extenal power supply? Is that output digital voltage level programable?

[Ivan.Chen]

I hope to use PXI 6514 to control 60 relays. It needs to source 50 mA current per pin. But I get some query about the HW of 6514.My question are as below:

1. In the PXI 6514's specification, it state as below:

"Power Requirements
+5 VDC (±5%)...................................... 150 mA
+3.3 VDC (±5%)................................... 300 mA, typical;
500 mA, maximum"

Is this the requirement of the external power supply which need to be provided by the user? If yes, as I can see, for this card each output pin can source up to 75mA current. It has 64 ouputs on the board, that means the current comsuption would be at least : 64*75mA=4800mA in total. It seems that the power supply as the specification stated can't source so much current. Is it a confliction?

2. Is the output voltage level of this card can be programable? I hope to get 5V voltage level when output high logic. Is it possible?

The advance is turely appreciated

[Napoleon_Buonaparte]

Hi Ivan,


1. The power requirements you posted is a power requirement from PCI slot. However, 6514 needs external supply as shown in page 4-6 of http://www.ni.com/pdf/manuals/372172a.pdf. In case that you need to source +5V for high logic, you need to use +5V power supply with at least .05*60=3A current rating. However, since relay needs high current when power on, I recommend at least +5V 5A power supply. Please also be informed that there may have some voltage drop on darlington output of 6514. However, it should be sufficient enough to drive relays.
2. The voltage output doesn't programmable. It changes by voltage you supply to each port as shown in above manual.
Please note that if you need an isolation for relay on each port, you need to use separate power supplies.


Regards, Kate

[Ivan.Chen]

Hi Napoleon,

I see. I would add a extenal power supply. 

Thanks for your quick answer!

BR,

Ivan

[BigApple0]

It would be helpful to post this excerpt from the user manual as well since the VCC voltage needs to be high enough for the onboard regulator to regulate.  It would also be nice if the user manual mentioned the current limit of the +5V supply.

The manual is not super clear on whether this +5V is generated internally or from the external VCC source.

To be clear, the manual should mention that +5V is in fact generated from the external VCC source.

Lastly, in the second note, shouldn't the manual say "INPUT VCC" instead of "Output VCC" since VCC is an input to the card and not an output?  Pretty sure it should since that's the way it works.

[rolfk]

Wording is always interpretative. The output here refers to the fact that it is for the Digital Outputs. The (user-provided) part indicates that it is an external power supply. Writing "output Vcc input" would also have been an option but really be even more confusing.

While I agree that the NI documentation is often rather limited and trying to be as undetailed as possible to avoid any possible error when hardware modifications are done later on, this one is fairly clear if you consider the technical possibilities.