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2182A data acquisition with labview

2182 Series Support
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Jack22
Posts: 6
Joined: June 7th, 2012, 11:43 am
Country: Canada

2182A data acquisition with labview

Post by Jack22 » July 6th, 2012, 9:49 am

Hello,

I'm using a 2182A nanovoltmeter connected by RS-232 to a 6221 current source, connected to my computer by ethernet. I want to extract the nanovoltmeter data and acquire the voltage at the specified rate.
So far, I've been able to controll the NPLC and the rate of the nanovoltmeter with the commands
:SYST:COMM:SER:SEND "VOLT:RATE:AUTO ON"
and
:SYST:COMM:SER:SEND "VOLT:NPLC 0.1"
But sometimes, quite randomly, even though it works, LabView sends an error. And those are the two only commands that seems to work quite properly. I use the «2182 A Query.vi» (from http://www.keithley.com/support/data?asset=53966).

When I try to ask
:SYST:COMM:SER:SEND "VOLT:NPLC?"
:SYST:COMM:SER:ENT?
Nothing is read and I have an error. I don't get that.

And when I try «READ?», the read.vi gives me sometimes the measurment, sometimes not, and most of the time an error with that.

Anyways, from what I understand, the «read?» command only gives one reading. What I'm actually tring to do is to get a series of measure, at the givin rate, but I don't know how to extract the data that I see on the front panel.

Thanks for helping!!
Jade

Mark W
Keithley Applications
Keithley Applications
Posts: 14
Joined: July 9th, 2012, 5:52 am
Country: United States

Re: 2182A data acquisition with labview

Post by Mark W » July 9th, 2012, 11:23 am

Jade,

Can you please provide all of the code you are using so I can see what you are doing?

Mark - Applications

Jack22
Posts: 6
Joined: June 7th, 2012, 11:43 am
Country: Canada

Re: 2182A data acquisition with labview

Post by Jack22 » July 9th, 2012, 12:01 pm

This is the file I use as a test, just to try to understand what's going on.
When I put the command
«:SYST:COMM:SER:SEND "*RST
:READ?"
:SYST:COMM:ENT?»
I get half of the time an answer, which is never the same than the one on the display.

In fact, what I want to do is to get continuously the data. Whent I do
«:SYST:COMM:SER:SEND "*RST
:INIT:CONT ON",STATUS%»
I also get only one answer, and only half the time, even though the display now displays continuously the data. I just don't know how to transfer it on the computer.

Also, when I repeat commands a certain amount of time, I always get errors completely randomly - sometimes it works, sometimes not. I can't get any pattern in it... Does it do the same to you?

Thanks!!
Jade
Attachments
commande2182.vi
(13.38 KiB) Downloaded 1224 times

Mark W
Keithley Applications
Keithley Applications
Posts: 14
Joined: July 9th, 2012, 5:52 am
Country: United States

Re: 2182A data acquisition with labview

Post by Mark W » July 10th, 2012, 5:37 am

Yes, I was able to reproduce your problem, and it appears you have discovered a firmware bug that needs to get updated. As a work around for now, you can always send an ENTer command after every remote rs232 query. This will clear the error que and allow the data buffers to be synchronized.

Mark

Jack22
Posts: 6
Joined: June 7th, 2012, 11:43 am
Country: Canada

Re: 2182A data acquisition with labview

Post by Jack22 » July 10th, 2012, 7:56 am

Hello,

I'm not sure to understand what you're telling me to do....
The command
«:SYST:COMM:SER:SEND ":INIT:CONT ON"
:SYST:COMM:SER:ENT?»
Dosen't give anything.... Still I don't know how to get the continuous data that appears on the display.

Thanks again!
Jade

Mark W
Keithley Applications
Keithley Applications
Posts: 14
Joined: July 9th, 2012, 5:52 am
Country: United States

Re: 2182A data acquisition with labview

Post by Mark W » July 13th, 2012, 6:54 am

Jade,

Sorry it took soo long to get back to you. I am unable to code a workaround for this firmware issue. The internal registers(6221) are getting corrupted when I try to send data via rs232 from the 2182A to the 6221. The measurement data is getting put into the error buffer, so you will not get repeatable results. I tried to come up with a way to reallign the registers after a call and was unsuccessful.

We are initiating a firmware fix for this problem. Unfortunately, the only solution I can think of in the mean time for you would be to use GPIB for your communication to both of your units via a KUSB-488B. This way you will be communicating and sending data from each instrument directly to the PC as opposed to having the 2182A data read by the 6221 and then sent to the PC. When the firmware fix is complete, it will be available on the Keithley website for download.

Hope this helps,

Mark

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