cRIO Module 9205 pin D0

[ill_dill]

Hi, 

I am trying to use pin D0 as digital output pin for an external boolean switch on a cRIO, module 9205. When I measure D0 using a voltmeter I get readings ~mV... Is there something special I have to do within the FPGA target LabVIEW program to get pin D0 to read 10 volts? 

Any hep would be appreciated! 

Thanks, 

Lane 

[GerdW]

Hi Lane,

unfortunately you don't attach the FPGA VI.

And in the attached RT host VI there is no item named "DO" to be found…

Btw. with FPGA VI you should attach the whole project including the lvproj file as that contains a lot of the needed (FPGA) definitions!

[ill_dill]

Hi, 

When using pin D0 as a voltage output, is there something special you have to do within the LabVIEW program in order to activate it? For example, for pins AI0-AI31, you can vary the input voltage in the "Module Properties" tab. Do you have to do something similar in order to get pin D0 to output a voltage? I would like it to output a voltage of 5V but right now when using a multi-meter to test the output I am getting readings of ~mV.  

Thanks for the help! 

-Lane 

[GerdW]

Hi ill,

instead of creating a new thread you should answer follow-up questions on your original message…

[toddy]

Can the 9205 actually output any voltages? I thought it was a AI device rather than AIO...

I think you may need an Analogue Output module.

[GerdW]

Hi Toddy,

the 9205 has a DO pin, which is accessable from the FPGA…

(See its manual!)

[rolfk]

I'm pretty sure the DO pin is not outputting any voltage but rather sinking an external current towards the COM pin. You need to have an external voltage source whose negative lead is referenced to the COM signal and a load that you connect between the positive output lead of that voltage source and the DO pin, and when you switch on the DO signal the current will be sinked to COM. Watch out that you do not exceed the specifications of that output pin.

[rolfk]

The datasheet says this:

Output high, VOH, sourcing 75 μA

Minimum 2.1 V

Maximum 3.3 V

Output low, VOH, sinking 250 μA

Minimum 0 V

Maximum 0.4 V

So it seems to be actively driven for both high and low level but only 3.3 V logic and 75 uA really requires you to connect a high impedance load (classic TTL logic gate draws way to much current for this to work.)

[ill_dill]

Thanks for the help everyone. I was able to figure out my problem. What I ended up doing was expanding the module 9205 in the LabVIEW program which allowed me access to pin D0. I then connected a logic switch to D0 which allowed my to change the voltage from 3V to 0V. I guess it was as lot simpler than I initially anticipated. 

Thanks for all the responses!