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Triggering the arb on E4438C

Question asked by reesebo on Jun 25, 2013
Latest reply on Jul 16, 2013 by PYong

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Hello,

I am using the IVI driver and writing c# for my E4438C VSG. I am currently able to trigger a burst waveform (~500ms) from the ARB, but in order to get it to function, I enable the RF, send the software trigger, sleep in software for 500ms and then disable the rf. Is there a way for the trigger to disable the rf after the burst is complete (all samples are transmitted) rather than to sleep?

I tried to just keep the RF on, but there is continuous energy transmitted from the VSG when it is idle that my application can not tolerate, so I am using the RF on/off.

Thanks

Reese

------- code fragment

                IIviRFSigGen drvr = (IIviRFSigGen)driver;
                drvr.DigitalModulation.Arb.TriggerSource = IviRFSigGenArbTriggerSourceEnum.IviRFSigGenArbTriggerSourceSoftware;
                drvr.DigitalModulation.Arb.SelectedWaveform = arbfile;
                drvr.RF.Frequency = xmtFrequency;      // set frequency
                drvr.RF.Level = xmtPower;            // set level (dBm)


                drvr.IQ.Source = IviRFSigGenIQSourceEnum.IviRFSigGenIQSourceArbGenerator;
                drvr.IQ.Enabled = true;
               drvr.RF.OutputEnabled = true;
                drvr.SendSoftwareTrigger();

                Thread.Sleep(500); // wait for burst to transnmit
                driver.RF.OutputEnabled = false;

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tabbott Jun 26, 2013 8:57 AM
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Hi Reese -

Have you tried using the Gated triggering? This will cause the waveform to wait for the first active trigger signal state to begin transmission, then repeatedly start and stop in response to an externally applied trigger signal. In the Arb format, the waveform plays during the inactive states, and stops during the active state.

*Ext Trigger* from the Trigger Source menu will be selected when the gated trigger mode is used. The length of each transmission depends on the duty period of the trigger signal and the gate polarity selection, which is set with the Gate Active Low High softkey. The polarity selection also determines which state (negative or positive) of the trigger signal causes an interruption in the modulating signal.

The external trigger signal connects to either the PATTERN TRIG IN connector or the Auxiliary I/O connector (PATT TRIG IN 2 pin). To select the connector, use the *Ext* Source softkey.

Gated Trigger SCPI: [:SOURce]:RADio:ARB:TRIGger:TYPE:GATE:ACTive LOW|HIGH

Hope this helps -
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- reesebo @ tabbott on Jun 26, 2013 2:57 PM
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  Hi Tabbott,
  
  Thank you very much for the reply. Do you think I might get away with using one of these for the trigger?
  http://sine.ni.com/nips/cds/print/p/lang/en/nid/201630
  
  Thanks
  
  Reese
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  - tabbott @ reesebo on Jun 27, 2013 9:04 AM
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    Hi Reese -
    
    This is the specification for the Ext Triggers from the Pattern Trigger connectors.
    
    The Pattern Trigger Connector accepts either a CMOS low to CMOS high, or CMOS high to CMOS low edge trigger. The minimum trigger input pulse width, high or low, is 100 ns. The damage levels are > +5.5 volts and < −0.5 volts.
    Or, if you would like to use PATT TRIG IN 2 pin from the Auxiliary I/O connector, it accepts a signal that triggers an internal pattern or frame generator to start single pattern output. Minimum pulse width is 100 ns. Damage levels are > +5.5 and < −0.5 V.
    
    You will need to review the NI USB-6501 data sheet to be sure that this can be used. At first glance, it seems so.
    
    Regards -
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    - reesebo @ tabbott on Jun 27, 2013 11:19 AM
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      I'll try it out and let you know.
      
      Thank you Tabbott
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      - tabbott @ reesebo on Jun 28, 2013 8:44 AM
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        You are welcome Resse - any time.
        
        Hey, ...after looking at the NI USB-6501 data sheet a little more, looks like it should work to provide an external trigger to the ES by programming it to suit.
        
        But if you want to send a S/W trigger rather than a hardware trigger, this can also be done. You would need to create the appropriate marker then route this to the Pulse/RF Blank circuit.
        
        If the marker polarity is set to positive then the output would only be enable during the waveform playback. So if the trigger is set to single then RF be off once the waveform stops.
        
        Until next time -
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        reesebo @ tabbott on Jun 29, 2013 8:19 PM
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        Hi Tabbott,
        
        I've given this a bit more thought, and it looks like using a marker and soft trigger is what I want to do. The C# IVI driver doesn't seem to implement the marker feature, however. Can I use the driver to issue scpi commands though? There is an interface that may do it, but if you could confirm that would save me some headache. Here is what I think might work:
        
        driver.System.IO.WriteString( scpi_command_string);
        
        the sequence of commands then might be:
        
        :SOUR:RAD:ARB:MARK:POL:POS
        :SOUR:RAD:ARB:MARK:RFBL:ON
        :SOUR:RAD:ARB:TRIG:TYPE SING
        
        when I trigger, I would still use the command:
        
        drvr.SendSoftwareTrigger();
        
        Thanks,
        
        Reese
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        tabbott @ reesebo on Jul 3, 2013 11:21 AM
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        Hi Reese -
        
        Yes, The commands seems right (which also depends on the driver methods used here). But basically you are setting up the:
        
        :SOUR:RAD:ARB:MARK:POL:POS   Marker Polarity
        :SOUR:RAD:ARB:MARK:RFBL:ON   Marker Routing
        :SOUR:RAD:ARB:TRIG:TYPE SING   Trigger Type
        
        And then send the software trigger.
        
        Don’t forget to create the marker over the active part of the signal as well.
        
        Regards -
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        reesebo @ tabbott on Jul 5, 2013 8:33 AM
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        Hi Tabbott,
        
        I have two more questions that will wrap this up for me:
        
        1. How do I "create the marker over the active part of the signal as well"?
        2. WIll the driver.system.io.writestring() function properly issue the scpi commands to the 4438, or do I need to open a separate telnet session to do so?
        
        thanks you very much,
        Reese
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        PYong @ reesebo on Jul 16, 2013 1:47 AM
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        Hi Reese,
        
        Todd will be out for next couple of days. Here's the response to your question:-
        
        Here is the command to set the marker:-
        
        [:SOURce]:RADio:ARB:MARKer:[SET] "",,,,
        
        So for the example below (let’s call the waveform “Test”), if we want to define the marker over the complete waveform (100 points) we would use:
        
        [ :SOURce]:RAD:ARB:MARK:SET "Test",1,1,100,0
        
        File_name = Test
        marker = 1 or Event 1
        first_point = 1
        Last_point = 100
        Skip_count = 0 – covers from 1 to 100 continuously
        
        For more SCPI programming questions, please refer to this SCPI command reference:
        Link: [http://cp.literature.agilent.com/litweb/pdf/E4400-90622.pdf]
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    - reesebo @ tabbott on Jun 28, 2013 10:49 AM
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      Hi Tabbott,
      
      I am intrigued with your comment:
      
      >>But if you want to send a S/W trigger rather than a hardware trigger, this can also be done. You would need to create the appropriate marker then route this to the Pulse/RF Blank circuit.
      >>If the marker polarity is set to positive then the output would only be enable during the waveform playback. So if the trigger is set to single then RF be off once the waveform stops.
      
      That should like exactly what I would like to do. Would you have any example .net code that would help me try this?
      
      I think we are approaching a nice solution.
      
      Thank you,
      
      Reese
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Triggering the arb on E4438C

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