E4418B Meter speed

[Kaspar]

Hello,

   I am using the Agilent E4418B power meter and I have looked at the examples Labview code and have modified it to work for me. I have noticed that the "Read" vi takes almost 1 second to get the measurement from the meter and update a numeric indicator. Does anyone know why this vi takes so long to ge tthe reading from the meter? Do I have something configured wrong with the meter?

Regards,

Kaspar

[pBerg]

Howdy Kaspar,

That doesn't sound like an unusually long time to receive a reading from your GPIB instrument. The act of taking a reading from it involves sending a read command to the instrument, waiting for the instrument to execute the read command, and receiving the data the instrument has read. So in all, a second to complete this process seems reasonable.


Message Edited by pBerg on 01-18-2008 12:17 PM

[Kaspar]

Hello,

  Thank you for getting back to me. The equipment I am working on cannot take high power values so I have to do the calibration quickly and accurately. I need to be able to apply the stimulus to the equipment in small increments (over a wide range) to improve the accuracy. So the 1 second a measurement may not be a good thing for me. I will see if the meter can be configured and/or triggered to be taking measurements all by itself, so that when a GPIB command happens the data for the most recent measurement is transferred to the GPIB master.

Thanks again for getting back to me and have a nice weekend!

Regards,

Kaspar 

[smercurio_fc]

You said "The equipment I am working on cannot take high power values so I have to do the calibration quickly and accurately." Performing a calibration on the power meter and taking a reading are two different things. Also, if you're relying on software to make sure you don't put a "high power" value to the instrument you're doing it wrong. You should never rely solely on software to protect your equipment.

That said, you should check to see whether averaging is on and what the measurement speed is configured to. These are both settings on the power meter that affect the amount of time it takes for the meter to make a measurement.


Message Edited by smercurio_fc on 01-18-2008 02:31 PM

[Kaspar]

Hello,

   I apologize for not stating my testing setup clearly. I am using the power meter to calibrate the equipment that I am working on, which cannot handle high levels of power for a extended period of time. Therefore I need to be able to take measurements very quickly when I am taking power measurements. I will investigate the configuration/etc of the power meter to see if anything can be done to obtain the measurement from it sooner.

Regards,

Kaspar 

[Rimasaurus]

Hi Kaspar,

In order to achieve a higher transfer rate on the GPIB bus, try to limit the physical distance between devices, and limit the number of devices on the GPIB bus.  Also, take a look at the following Developer Zone tutorial: Eight Ways to Increase GPIB System Performance.

Regards,

Rima

[PierreTRT]

Hi Kaspar,

I'm making a test bench for MEMS switches measurements and I have to use two cards: a DAQ card (NI PCI 6711) and a GPIB card. Actually I have to generate two signals with the DAQ card (this is ok, it works) and I have to make power measurements with the GPIB card and power meter E4418B (power sensor E4412A).

I am trying to synchronise the generation and the measurements but I don't have managed yet to perform this. I would be very interested if you can give me some advice to use the trigger of the power meter. How did you do? Did you use a state machine?

Material I use:

LabView 7.1 and NI DAQmx 7.2

Thanks,

Pierre

[Kaspar]

Hello,

   I have not worked on the project that used the power meter in a while, but here is how I left it.  I was trying to automatically calibrate an amplifier by adjusting the level of the input signal and using the power meter to observe the output power level. What I observed is that the power meter took a long time to accurately measure the power level, which increased the time I had to wait to get a correct  power measurement.   When the amplifier was at low power levels, the time did not make a difference, but at high power levels the amplifier could/would/did overheat and bad things did happen to the amplifier. Unfortunatley that project was canceled before I was able to come up with a fix. 

  I have also used MEMS before and you need to be aware of the scenario that I had, make sure that you do not blow something up because the time to get a accurate power level from the meter exceeds the duration that your device can sustain a power setting before it goes up in smoke.  You may have to have a really nice cooling scheme for your MEMS device so that it does not burn up while you are waiting for the meter to give you a accurate power reading. If you have any other questions, please feel free to reply to this posting.  

Regards,

Kaspar

[auto tech]

i am new to labview .can u send the code

[auto tech]

i am new to labview .i have agilent powermeter (437b) .can any one  send code for me.