E4416A power meter visa read slow

[Grant_C]

Hi all, i am parsing the trace data from a Agilent E4416A power meter using a visa write command and then a visa read command.  For 1 iteration, this is fine.  But i want to cycle this 100 times and am seeing about a 1second delay on the read command.  Is there anyway to speed the read process up.  Cant believe that the instrument would take this long to process.

Thanks

[smercurio_fc]

It all depends on how you configured the measurement (i.e., resolution, speed, etc), and which command you're using (i.e., measure, read, or fetch) to get it. The meter's documentation will tell you the expected measurement time based on the resolution and speed, and it will also tell you the difference between measure, read, and fetch.

[Grant_C]

Hi, i am not instructing the power meter to take a measurement.  I am simply asking for the trace data using a visa write command and then a visa read command.  The manual does not giveany information on how long the visa read command should take to process.

Regards 

[Henrik_Volkers]

Now it's the point to RTFM to understand how the powermeter works, how to set it up that it fit your needs and then take a look at the NI Driver database if you can find a siutable driver or send the commands needed in your own code.

Possibly your current setting will do a 1s averrage, so every get/read/fetch command will wait for the current measurement to finish....

[Grant_C]

Hi all, for future readers, this is a problem with the instrument.  The only way round the visa read delay problem is to reduce the resolution, ie HRES, MRES or LRES.  Although i need to use HRES so will have to accept that retreiving the trace data will take 1second per triggered cycle.

Thanks for your help. No need to RTFM.  Answer is here. 

[smercurio_fc]

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Grant_Cargill wrote:

Hi all, for future readers, this is a problem with the instrument.  The only way round the visa read delay problem is to reduce the resolution, ie HRES, MRES or LRES.  Although i need to use HRES so will have to accept that retreiving the trace data will take 1second per triggered cycle.

Thanks for your help. No need to RTFM.  Answer is here. 

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Saverio starts talking to himself... "Did I not say something about the way the power meter was configured? As in possibly its resolution setting...". 

This is not a problem with the instrument. We have E4419 power meters in our lab and they behave the same way. Because that's the way they're supposed to behave.  If you ask an instrument to make a measurement with a higher resolution then it will take more time to make the measurement. In fact, there is a table in the manual that shows the relationship between resolution, speed, and the amount of time it takes to make a measurement. The VISA Read is waiting for data from the power meter, and it's not ready to give it to you because it's busy doing what you told it to do.