VISA Read Timeout - thermal chamber

[gohawks12]

Hi,

I am trying to develop a thermal chamber program that runs 24/7.  I am testing it out but there is always a VISA write or read problem with the chamber after running it for around 8+ hours.  Every five seconds, the program queries the chamber for it's status bits or chamber temperature.  These operations are performed without error initially but after around 8+ hours (no exact duration, it varies for each execution), there is a timeout from either the VISA write or VISA read when trying to read the chamber temp/status.  I have logged the IO trace (attached).  I have made sure that no other VISA instrument is communicating during the time the program communicates with the chamber by using semaphores.  I cannot seem to figure out why this would happen. I do have delays between the VISA write and read VIs.  Anyone have any ideas? 

Please see the attached screenshot of the IO Trace.

Any help is appreciated.  thank you!

[GerdW]

Hi gohawks,

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@gohawks12 wrote:

but after around 8+ hours (no exact duration, it varies for each execution), there is a timeout

Anyone have any ideas?

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Well, the working day ends after ~8 hours… 😄

Your device uses GPIB communication: which GPIB port do you use?

Are there any power saving settings active with that specific port?

(When talking about hardware problems it might help to specify the hardware you are using!)

[ANON12345]

Hi I am the OP. Just using a different account. I am using this chamber: EC127 http://www.sunelectronics.com/Temperature-Chamber-Refrigeration-Model.html I am using GPIB port 6. I am not sure of the power saving settings but I will check. Thanks for the tip.

[crossrulz]

What GPIB controller are you using?

What is the total length of GPIB cables to the temperature chamber?

What other devices are on the GPIB bus?

[ANON12345]

I’m using the blue NI GPIB USB HS. 

cable length is not that long. Probably 6-10 ft. 

other devices are two PSUs. Keysight N57xx

and DMM switch matrix. Keithley 2750. 

I used semaphores to ensure they are not communicating simultaneously 

[billko]

USB.  Probably the something to do with the power settings for this device.  The PC probably makes it go to sleep.  Make sure your PC's current power profile doesn't allow USB devices to go into power saving mode.

[crossrulz]

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@ANON12345 wrote:

I used semaphores to ensure they are not communicating simultaneously 

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Semaphores should not be necessary since the GPIB controller will handle all of that mess.

My main suspect is the USB hub power settings.  Make sure Windows is not allowed to turn those off to "save power".

[ANON12345]

Billko and crossrulz, 

thanks for the tips. I will change the usb power setting and let you know if that works. Thank you!

[gohawks12]

So before I changed the USB power settings, I  re ran the test but I put an error clear VI after the chamber read VI just to see what would happen.

It looks like the chamber wasn't able to read momentarily since it read a measurement of zero but I guess after the error cleared then it was able to read properly again shortly after...

I am reading from the chamber every 5 seconds.

[billko]

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@gohawks12 wrote:

So before I changed the USB power settings, I  re ran the test but I put an error clear VI after the chamber read VI just to see what would happen.

It looks like the chamber wasn't able to read momentarily since it read a measurement of zero but I guess after the error cleared then it was able to read properly again shortly after...

I am reading from the chamber every 5 seconds.

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That's like fixing your smoke detector by wearing ear plugs.  FIX THE PROBLEM, DON'T SWALLOW THE ERROR.