Current limit at counter (ctr)

[dotNet_to_LabW]

Hello,

I am having following situation:

- Using NI-6351 ctr1 to output a signal with frequency 50 KHz and 0 Hz to a device connected to it.

- After I have supplied mentioned signal and performed my function, I use ctr1 as port2/line5 digital input and drive it to tri-state.

It works fine except one major drawback:

- I do not get 5V at the output but far lesser (ca. 4.4 V). I think that digital ports/ctr1 has current limitations and the device connected to it has draws some current too. I can not anything lesser than 4.8V to perform the desired function.

- I could have used an analog port (AO) for the above purpose but there again I have 2 issues:

 - How can I output frequency at AO?

 - Moreover after I have performed desired task on device, I can not bring analog port in tri state (of course, I can Reset NI-6351, but this is not at all wished)

Can you please suggest me some better solution?

Thanks in advance.

Regards

RB

[dotNet_to_LabW]

update..

Now I know how to output frequency at AO port, but still do not know how to drive an AO port in tri state? According to NI, only digital ports can be driven to high impedance state. What about analog ports?

[ADagli]

Hi RB,

I want to help you with your questions.

First:

Yes, you have current limitations up to 1V.

You will find an overview about the limitations for your Hardware here: http://sine.ni.com/ds/app/doc/p/id/ds-100/lang/de (Current Limits)

So, together with the device connected to the port which also draws current you will have problems here. How about using a buffer stage?

Second:

No, there is no tri-state functionality on analog outputs. This is a property of digital channels.

Best regards,