Digital outputs

[Shawn HUSCO Auto]

I am working on an application in which I want to cycle a number of relays.  When I run the program all the digital outputs stay at 5 volts and do not change during the test.   I have attached copy of my program as it exists so far. Any help would be appreciated

[Shawn HUSCO Auto]

I appologize I forgot to include this earlier....I am trying to drive the relays using digital outputs on a PCI 6711 through an SCB 68. 

[Online_Courses]

Message Edited by Online Courses on 08-04-2009 12:30 AM

[Online_Courses]

Message Edited by Online Courses on 08-04-2009 12:34 AM

[Doiron]

Hi Shawn,

I took a look at your code and it seems correct as long as you have the channels hooked up properly (I can only see the tasks being selected).

Have you tried using test panels in the Measurement and Automation Explorer to verify that your device is working?

[Shawn HUSCO Auto]

I used DAQ MX to test the digital outputs of the card and they switch when I use the test panels.  That is why I figured it had to be something in the way that I wrote the code. 

[Doiron]

Hi Shawn,

I took a closer look at your code and it doesn't appear that you ever write a "false" to a digital line, only "true".

Is there a case where you have written a false and I don't see it? It appears to me as if that code should always output 5V (true).

[Shawn HUSCO Auto]

In the run states I usually wire a false to the dgital out after the while loop and before I clear the task unless the valve will be open in the next step of the sequence, but the more I think about that the more I think that will not work how I want it to either.  Essentially I want all the digital outputs to be false in the idle state.  Do I have to set all the digital outputs to false at the beginning of my code or is there a way that I can defalut them all to false?  It seems like the outputs are all just high. 

[Doiron]

Hi Shawn,

Unfortunately I am not by a computer with LabVIEW, so I can't tell if you are wiring a false anywhere, however I can tell you that you do need to write to the card to receive a value, there is no default state this card will return to on each iteration.

[Doiron]

Hello Shawn,

You are writing a "false" to "Digital Out Valve 3" task in the "Purge Run" state and to Vales 1, 4, and 5 in the "Switching Leakage Run" state. Could you please place a breakpoint immediately after the digital write where you write false so we can measure the voltage at this point?