Hi Garvin,
           One thing that might be affecting this is the hardware set 2 second timeout on the USB to GBIB interface. As far as I'm aware this only slows things down if something times out, when no timeouts occur it runs as fast as the National instruments USB to GPIB. I'm not sure if this affects all USB to GPIB made by HP and or Agilent or only some. We discovered this with our Agilent USB to GPIB and it was confirmed by Agilent support. We haven't found any way around it (that's why we buy NI USB to GPIB now).
Â
Ben
 _____ Â
From: Garvin, Al [mailto:al.garvin@lmco.com]
Sent: 13 February 2006 15:14
To: VRF
Subject: [vrf] Timing issue using HP 82357 usb to GPIB interface
I have a program running on a laptop under Vee 7.03 which makes an S11 measurement on an HP 8753ES network analyzer. I am able to use one of two interfaces with it.
One is a National Instruments PCMCIA-GPIB card and the other is the HP 82357 usb to GPIB interface. I only have one of the interfaces in the laptop at any one time.
I am using an "On cycle" object set to 3 seconds to control the measurement. Using the NI card it takes 382 ms to make the measurement and return the data. Using the
HP 32357 interface it take 2.82 seconds to make the measurement and return the data. Same code and same instrument and same driver (AG875X). Is this normal for the
HP interface to take so long to make the measurement? I eventually want to set the "On cycle" object to 1 second.
 Thanks,
Al Garvin
Lockheed Martin
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           One thing that might be affecting this is the hardware set 2 second timeout on the USB to GBIB interface. As far as I'm aware this only slows things down if something times out, when no timeouts occur it runs as fast as the National instruments USB to GPIB. I'm not sure if this affects all USB to GPIB made by HP and or Agilent or only some. We discovered this with our Agilent USB to GPIB and it was confirmed by Agilent support. We haven't found any way around it (that's why we buy NI USB to GPIB now).
Â
Ben
 _____ Â
From: Garvin, Al [mailto:al.garvin@lmco.com]
Sent: 13 February 2006 15:14
To: VRF
Subject: [vrf] Timing issue using HP 82357 usb to GPIB interface
I have a program running on a laptop under Vee 7.03 which makes an S11 measurement on an HP 8753ES network analyzer. I am able to use one of two interfaces with it.
One is a National Instruments PCMCIA-GPIB card and the other is the HP 82357 usb to GPIB interface. I only have one of the interfaces in the laptop at any one time.
I am using an "On cycle" object set to 3 seconds to control the measurement. Using the NI card it takes 382 ms to make the measurement and return the data. Using the
HP 32357 interface it take 2.82 seconds to make the measurement and return the data. Same code and same instrument and same driver (AG875X). Is this normal for the
HP interface to take so long to make the measurement? I eventually want to set the "On cycle" object to 1 second.
 Thanks,
Al Garvin
Lockheed Martin
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There is a downloadable utiltiy from Microsoft "UVCView.x86.exe" (also included with recent release of IO Libraries - "C:Program FilesAgilentIO Libraries
Suite inusbusbviewusbview.exe") which gives information on the USB ports. It indicates "Device Bus Speed" which may not be the USB ports actual capability. It also lists the "RootHubs" and the ports under each RootHub. Here is a (partial) sample of the
info:
...
ConnectionStatus: DeviceConnected
Current Config Value: 0x01
Device Bus Speed: Low
Device Address: 0x01
Open Pipes: 1
...
My undertanding is that the available resources of a RootHub are shared by the ports that it serves. Which may mean that each port (if a device is connected and active) may perform at a reduced/shared speed. The performance of high-speed device may also be affected by a slow-speed device connected thru the same RootHub.
_Vinod
--- "Garvin, Al" <al.garvin@lmco.com> wrote:
> Vinod,
> I'm not sure what my USP port speed is. How can I tell? The only
> other thing connected to the usb port is a mouse and I am using
> version
> M.01.01.04 of the IO libraries. I will download the latest version of
> the libraries from Agilent and see if that make any difference.
> Thanks,
> Al
>
> -----Original Message-----
> From: Vinod [mailto:papineni_vinod@yahoo.com]
> Sent: Monday, February 13, 2006 7:58 AM
> To: Garvin, Al; VRF
> Subject: Re: [vrf] Timing issue using HP 82357 usb to GPIB interface
>
>
> Al,
>
> What is the speed of your USB port? Are there any other USB devices
> connected to any of the other USB ports on your laptop? What is the
> version of IO libraries you are using? I recall reading a note about
> speed improvements made with a newer release of IO libs & 82357A.
>
> -Vinod
>
> --- "Garvin, Al" <al.garvin@lmco.com> wrote:
>
> > I have a program running on a laptop under Vee 7.03 which makes an
> > S11
>
> > measurement on an HP 8753ES network analyzer. I am able to use one
> > of two interfaces with it. One is a National Instruments PCMCIA-GPIB
> > card
>
> > and the other is the HP 82357 usb to GPIB interface. I only have one
> > of the interfaces in the laptop at any one time.
> > I am using an "On cycle" object set to 3 seconds to control the
> > measurement. Using the NI card it takes 382 ms to make the
> measurement
> > and return the data. Using the
> > HP 32357 interface it take 2.82 seconds to make the measurement and
> > return the data. Same code and same instrument and same driver
> (AG875X).
> > Is this normal for the
> > HP interface to take so long to make the measurement? I eventually
> want
> > to set the "On cycle" object to 1 second.
> > Thanks,
> > Al Garvin
> > Lockheed Martin
> >
>
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