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Back Panel on DSO9104A

Question asked by natant on May 13, 2013
Latest reply on May 29, 2013 by algoss

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I use the above, and have all the documentation files that come along with it, but I cannot seem to find any explanation for the five BNC connectors on the back. Can someone point me to a file that explains them?

The only thing I know is the name of each connector since it is written on the instrument. But besides that - nothing. I am especially interested in the "trigger out" connector since I want to use the oscilloscope to trigger a microcontroller.

Edited by: Natan_T on May 13, 2013 2:00 PM

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algoss May 14, 2013 5:24 AM
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I don't know why that information isn't in the User's Manual, and there's only a cursory mention in the Service Guide. I'll see if I can get that fixed.

The "Trigger Out' is driven every time there's a valid trigger to the scope. The easiest way to see what it does is as follows:
- Connect a cable or probe from Channel 1 to the Calibration Output.
- Autoscale
- Make sure the Scope is in 'Triggered' mode, not Auto.
- Connect a BNC cable from 'Trigger Out' to Channel 2 and turn Channel 2 on.

You should now see the pulse that Trigger Out produces. You can zoom in and see the delay from the Trigger, the voltage, and the width.

Note that this pulse doesn't get created if the scope does an 'Auto' trigger.

Al
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- natant @ algoss on Dec 23, 2014 5:46 AM
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  Thanks for your response. I did as you said, using an external pulse generator to generate a square wave on channel 1. Indeed there is a pulse on channel 2. It is delayed by about 37 nsec, its height is just above 4V and its width is about 20 nsec. Do those numbers sound reasonable?
  
  Also, I do think it's important to update the User's Guide, as it is currently incomplete.
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  - algoss @ natant on May 20, 2013 4:59 AM
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    Yes, that pulse seems reasonable. It's high enough and long enough to be used as a TTL trigger, but not too big to be safe for other logic families.
    
    As I had previously said, I'll see about getting the manual and help files fixed.
    
    Al
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natant Dec 23, 2014 5:46 AM
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I would like to return to my original question since I think I did not understand something. I have attached a screenshot of what I am describing (trigout1.jpg). Channel 4 (red)is a 10MHz square wave from an external pulse generator (Agilent 81150A). Channel 1 (yellow) is connected to trigger out on the back panel. I want the yellow pulse to appear after every rising edge of the red pulse. Is it possible?

My overall objective is as follows: Receive a square wave on channel one (frequency 10kHz, period 100 usec) and connect trigger out to a microcontroller in order to give an interrupt every 100 microseconds.
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- algoss @ natant on May 29, 2013 6:32 PM
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  No, you can't do that. In general, here's what a scope does:
  1) Start capturing data, while looking for a trigger
  2) Find a trigger
  3) finish filling memory
  4) display data
  5) Go back to 1)
  
  On some scopes, it goes back to 1) after 3), and displaying data happens in parallel with the capture of the next data.
  
  In any case, there's a maximum re-trigger rate for every scope. To get the maximum rate, you have to set the depth to the smallest number possible, something like 16 samples. The maximum rate isn't defined for the 9000 series of scopes, but you can find out what it is by hooking up a counter to the 'trigger out' and putting in a high frequency sine wave, like maybe 1 GHz.
  
  Note that the re-trigger rate isn't constant, and even if it's fast enough for your use, on average, there's no guarantee that you will trigger on every edge on the input.
  
  You would be better off building a circuit to generate a pulse on every edge of the square wave.
  
  Al
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