Sync. of multiple PCI Analog Output cards .NET

[MAN_Diesel_AJL]

Using 3 PCI 6713 cards to generate analog data that has to be synchronized. 

The problem is that the first card is one sample ahead of the two others. I am unsure of how to make the synchronization correctly. 

First a clock generator is setup at dev0:

      private void SetAndStartRPMClock( ICallContext context )      {         double frequency = ( ( m_RPM * 4.0 ) / 60.0 ) * ( (double)m_SimulationData.TriggerPulses.Value );         m_CurrentSampleFrequency = frequency;         if ( m_RPMTask != null )         {            m_RPMChannel.PulseFrequency = frequency;         }         else         {            m_RPMTask = new Task( "RPMGeneratorTask" );            string name = m_Generator1.GetPhysicalChannels( PhysicalChannelTypes.CO, PhysicalChannelAccess.External )[ 0 ];            m_RPMChannel = m_RPMTask.COChannels.CreatePulseChannelFrequency(               name,               "RPMClockGenerator",               COPulseFrequencyUnits.Hertz,               COPulseIdleState.Low,               0.0,               frequency,               0.5 );            m_RPMTask.Timing.ConfigureImplicit( SampleQuantityMode.ContinuousSamples, 1000 );            m_RPMTask.Start();            context.Log( String.Format( "Setting RPM Generator to {0}[Hz]", frequency ) );         }      }

 This is routed to RTSI0

         DaqSystem.Local.ConnectTerminals(String.Format("/{0}/Ctr0Out", m_Generator1.DeviceID), String.Format("/{0}/RTSI0", m_Generator1.DeviceID), 0);

 And the 3 cards are setup:

               //"RTSI0"               foreach ( Task t in m_DeviceTasks )               {                   if (t != null) t.Timing.ConfigureSampleClock("RTSI0", 1000.0, SampleClockActiveEdge.Rising, SampleQuantityMode.ContinuousSamples, (int)SAMPLE_LENGTH);               }               m_DeviceTasks[1].Triggers.StartTrigger.ConfigureDigitalEdgeTrigger(String.Format("/{0}/ao/StartTrigger", m_Generator1.DeviceID), DigitalEdgeStartTriggerEdge.Rising);               if ( cylinderCount > 8 )               {                   m_DeviceTasks[2].Triggers.StartTrigger.ConfigureDigitalEdgeTrigger(String.Format("/{0}/ao/StartTrigger", m_Generator1.DeviceID), DigitalEdgeStartTriggerEdge.Rising);               }

It's getting a bit late now, and I am unsure what information You need but please ask and I will supply. 

/Allan Juul Larsen

MAN Diesel

Copenhagen DK. 

[Morini]

Hi Allan,

When using an RTSI cable, you will need multiple tasks for multiple cards. The sample clock for the slave tasks will be the master sample clock.

From the attached the code it seems that you are doing just that.

An addition tip you should remember when programming is to call the slave tasks before the master task so that the acquisition will start at the same time.

You might already seen this vb example on Multiple Device Cont. AI sync:

"C:\Documents and Settings\All Users\Documents\National Instruments\NI-DAQ\Examples\DotNET1.1\Synchronization\Multi-Device\AIContAcquisition\vb"

Please let me know if this helps.

[MAN_Diesel_AJL]

Hi Dennis.

Thanx for the reply, I actually looked a long time to find the examples, the are nice to have.

I have 4 tasks:  

1 signal generator. (m_RPMTask) 

3 analog output tasks (m_DeviceTasks[ 0 1 2 ]) 

Should I have m_RPMTask and m_DeviceTasks[ 0 ] in one task? they use the same HW device. 

At the moment the m_RPMTask is started first would it be more correct to start this as the last one? 

/Allan

PS. I think I have had contact with You or Your college (Eirikor) some time ago regarding the same matter? Case # 780510 

[Morini]

Hi Allan,

It is not possible to have AO and AI in just one task. You need to split them up into two serparte tasks.

Depends on what you want to do, you can try to start the AO task first on the Master Device and then AI tasks on Slave devices and at last start the AI task on the Master device. This way all three AI tasks should be synchronized to the AO task.

Hope it makes sense.

[MAN_Diesel_AJL]

Just to in form. 

I found the error that made card 2-3 ofsett one sample. I removed the triggerstart lines to card 2,3 these were redundant. The cards start when the generator is started via ao/sampleclock from card 1.  

/Allan