programming ni6520

[jbrown60]

Has anyone had experience in programming the NI-6520 Relay card using CVI?  I am using CVI 2013 with DAQ 15.0.

NI-MAX shows the card installed and can access it via the Test Panel.

I just need some simple command lines for flipping the relays.

[yamadj]

Hey jbrown60,

Have you already tried the examples that ship with CVI?

Text Based NI-DAQmx Data Acquisition Examples - http://www.ni.com/example/6999/en/#.NETDIO

in that document it states that "The default installation directory for LabWindows/CVI examples is C:\Documents and Settings\All Users\Documents\National Instruments\CVI\samples\DAQmx."

Also check out the support reasources!

NI LabWindows™/CVI Technical Resources: Getting Started, Support, and Downloads - http://www.ni.com/lwcvi/technical-resources/

[jbrown60]

My installation of CVI did not come with the samples in that directory.

The problem is slightly more complicated in that my develoment machine is a laptop and the target machine is a desktop with the 6520 in it, so I am programming blind.

I have installed the NI-DAQ 15 that came with the card on both machines (which hopefully won't screw up previous development packages).

The desktop sees the NI-6520 as "Dev1".  On the test panel: I can select port 1, and select the state under port1/line0:7 to change the state of relays. So I know I should be able to talk to it somehow. Is the board considered a switch or digital I/O.  I'm just looking for maybe ten lines of code that will connect me to the board and activate a relay.

[RobertoBozzolo]

1. A correct install of DAQmx should come together with the appropriate examples, maybe located in a different folder on disk. You can use the example finder (Help >> Find examples... menu item in CVI IDE) limiting the search on your specific board: see this post where I explain how to do this

2. Even if your PC hasn't the correct hardware installed, you could create a simulated device for your board and test your software agains it: see this tutorial on simulated deviced in DAQmx

[jbrown60]

Thank you Roberto for directing me to some very useful information.

Using the Help files for the NI MAX install I was able to create a virtual instrument.

I was also able to find the CVI example program "WriteDigPort" which sets up a DAQmx task to write to the board, which in this case is the 6520.

As expected it really comes down to only about 6 lines of code.  I will post the controlling function when I get it incorporated so that others may not have to spend days hunting.

[RobertoBozzolo]

You're welcome!

[jbrown60 · Accepted solution]

As promised. A simple set of routines to control the 6520 under Win7, CVI 2013, NI-DAQmx 15.5

Required include files:
#include <NIDAQmx.h>
#include <DAQmxIOctrl.h>

/* declare global for Task Session */
static TaskHandle taskHandle = 0;

/* main function calls Init6520Sesn to get taskHandle and start DAQ task */
int Init6520Sesn( )
{
   int32 rtnStatus = 0; 
   char chan[256];
 
 /* NI MAX address location for the 6520 shows as Dev1,
 * port0 controls sensors, port1 controls relay state
 * line0:7 addresses the 8 relays on the board
 */
   sprintf(chan,"Dev1/port1/line0:7"); 
 
   /*********************************************/
   // DAQmx Configure Code
   /*********************************************/
   rtnStatus = DAQmxCreateTask("",&taskHandle);
   rtnStatus = DAQmxCreateDOChan(taskHandle, chan, "", DAQmx_Val_ChanForAllLines);
 
   /*********************************************/
   // DAQmx Start Code
   /*********************************************/
   rtnStatus = DAQmxStartTask(taskHandle);
   /* put error handling code here */
 
   return 0;
}

void Switch6520Relays(int nRelayState )
{
   uInt32      data;
   char        errBuff[2048]={'\0'};
   int32  written;
   int32  rtnStatus = 0;
 
   /*********************************************/
   // DAQmx Write Code
   /*********************************************/
   data = nRelayState ; // convert int to UINT32
 
   rtnStatus = DAQmxWriteDigitalU32(taskHandle,1,1,10.0,DAQmx_Val_GroupByChannel,&data,&written,NULL);
   if(rtnStatus != 0)
   {
      DAQmxGetExtendedErrorInfo(errBuff,2048);
      MessagePopup("DAQmx Error",errBuff);
   } 
}
// END 6520 Functions

/* Add shutdown calls when session no longer needed, in this case when the application closes */
int CVICALLBACK panelCB (int panel, int event, void *callbackData,
  int eventData1, int eventData2)
{
   if (event == EVENT_CLOSE)
   { 
      DAQmxStopTask(taskHandle);
      DAQmxClearTask(taskHandle);
  
      QuitUserInterface (0);
   }
   return 0;
}