Kikusui PLZ334WL Intermitent USB Failure

[Ryan_G_EE]

I am trying to write an automated test program in LabVIEW using a Kikusui PLZ334WL. However, it appears to "drop out" intermittently, causing a Resource Not Found error. The other USB controlled instruments are working fine, and the Kikusui works fine for a while, and then disappears. A power-cycle of the instrument appears to be the only thing that will bring it back...which is of course counter productive for automated testing...

One of the other engineers that I work with says he has seen this in the past when using USB, but not when using serial communication with this instrument.

Has anyone else seen this issue, and have an idea why it may be occuring? I contacted Kikusui, but have not gotten a response yet.

[nyc_(is_out_of_here)]

Too many USB devices on the hub hogging power?

[Ryan_G_EE]

Tried using an external powered USB hub, didn't fix the problem with the Kikusui, and the other instruments seem to be working fine. Also, I notice that the Kikusui does not report a USB input current requirement in the Windows Device Manager, whereas all of the other instruments report back 100mA...the Kikusui just says 0mA...assuming that this is not accurate, this is one of the reasons I tried the powered hub, since it is capaple of up to 500mA per port.

[Perry_S]

Hi R. Gibson,

Have you tried the other USB ports on your machine? Is the same behaviour exhibited? Let me know.

Regards,

Perry S.

[Ryan_G_EE]

I tried it on another machine and the issue seemed to go away. Not sure if it is the instrument, PC, or USB port at this point. Will be trying a few different configs this week to see if I can track it down.

[Perry_S]

Hi R.Gibson,

It sounds like a hardware issue and not a software issue. You have changed the PC now you can change the other variables and see which one stands out. Has this set up ever worked on a consistent basis? Let me know.

Regards,

Perry S.

[Ryan_G_EE]

I know this is digging up an old thread, but I'm still dealing with this issue. While most of the intstruments that I am trying to control all work nicely together (regardless of how they are connected to USB) the Kikusui electronic loads do not. These particular instruments get very intermittant during repeated opening and closing of the resource using VISA as I cycle through all of the instruments. They always hang up on the Open command...but not every time...it can happen anywhere from once in 10 loops, to nearly every loop. I always open and close each instrument before moving on to the next instrument, never leaving a resource open.

I have discovered that moving the USB connection around does seem to affect this issue. Just yesterday I discovered that my recent issues were allieviated by moving the Kikusui USB cable from the hub that all the other instruments are connected to, directly to another USB jack on my laptop.

I tried using the USB hub both powered and unpowered with no affect. I now only use USB cables with inductive chokes on each end, in order to reduce common mode noise in the cables. No other instrument has any issue with this setup. Why do these instruments have this issue? Other than connecting to another USB port, is there anything I can do from a software/configuration perspective to improve the robustness of this connection?

Another issue that I have is that I tried setting the VISA timeout to various values from 2000ms to 10000ms, and it doesn't seem to matter. The instrument always times out at exactly 2 minutes when this communication issue occurs. It is good that it eventually times out, but why doesn't the VISA timeout work? I am able to get the connection to reset by unplugging the USB and reinserting it....but unattended, after exactly 2 minutes the instrument will eventually release and allow the code to retry to open the resource. Sometimes it takes 2-3 tries before it is able to actually open, adding considerable time to the automated testing. If I could get the VISA timeout to actually work, I could shrink this 2 minute delay down to a few seconds, which would be nice...but still obviously not fixing the problem...

So, in conclusion, two questions:

1) Is there any way to improve the robustness / reliability of the USB connection to this instrument through some VISA setting or something (regardless of how the instrument is connected)

2) Is there any way to fix the VISA timeout property so that it actually has an effect on timeout?

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...for what it's worth, this sounds like a very similar issue:

http://forums.ni.com/t5/Instrument-Control-GPIB-Serial/Intermittent-visa-error-BFFF0011-with-viOpen/...

Referring to message #4, I hate resorting to leaving the resource open for the whole test, but this is the only suggestion that I have seen that seems like may work...

[weipeng9698]

Menu => configuration => interface => change control to USB