GPIB-USB-HS Single read then time out

[g4bch]

Hi

I am trying to use a GPIB-USB-HS to control an old HP 436 power meter. using Labview.

I have an Agilent 82357A USB to GPIB interface, and using that my routine which is a VISA open  followed by VISA read then close works fine every time I call it. Using the same routine with the GPIB-USB-HS it will read correctly once and then when called again it imes out with the HP436 stuck in remote. If I switch off the power meter and switch it back on aagin I can read it, but again only once.

Serching the forum I found reference to setting the EOS byte to LF. Using NI MAX I've done this , but it makes no difference. I've ried pretty much all combinations in the termination settings with the same result..

I've also found reference to sendign CR LF to terminate commands, but can't find any way of doing that using the VISA blocks.

The reason I'm wanting to use the USB-HS rather than just stick with the Agilent adaptor is a move away from 32 bit computers to 64 and the lack of 64 bit drivers for the old adaptor. It works with W7 32 bit so I could kick the can down the road a bit, probably unitl I retire and then it won't be my problem by forcing the test guys to use 32 bit W7, but I'd like to get it sorted properly, so If anyone has any ideas I'd apreciate hearing them.

Thanks

Peter

[NataliaS]

Hey Peter,

This is a bit of try and see if it works issue, let's start by the CR LF commands in VISA and see if this gets HP436 to terminate.

https://www.ni.com/en/support/documentation/supplemental/06/termination-characters-in-ni-visa.html

Let me know if this helped you get further!

Kind Regards,

-Natalia

[Albert.Geven]

Or is it the busspeed that is too fast...?

make the busspeed 2 microseconds. This hardly infuences new instruments but old ones could get lost.

[JÞB]

That legacy HPIB interface operates a bit oddly by modern standards.  

Yet, we do have access to some of the properties that were more commonly used 50 years ago and are less common now.

IO Prot(ocol) Normal tells the HS capable GPIB Controller to slow down to legacy speed.  Unaddress TRUE tells the controller that the darned old device needs to be "Untalked" and "Unlistened" after every Read or Write.

[g4bch]

Thanks to all who have replied. I've tried all the suggestions, and more, but to no avial.

From the help window, the terminate character, when set in the property node seems to only affect reading from the instrument; I.e LV is looking for the instrument to send the LF character. The power meter I have is expecting a LF to terminate the command sent to it. I've tried enabling the Send End property, it should be enabled by default any way, but it has no effect. I cant find a property to force a given termination character at the end of the VISA read command. I've tried the simple idea of putting a VISA write after the read, but that did not work either. Not that I expected it to, but thought it was worth a try.

For what it is worth the vi I am using is attached, I hope.

Peter