Agilent 34790/RTD

[JLS@Micro]

Designed fixture to originally collect temperatures using thermal couples to connected to an Agiglent 34970a. Decided to convert to RTD's, I have changes all the settings within my "Config Temp" and "EZ Temp" sub VI's. Once a value is placed within the "Scan List" my Agilent defaults to the 100ohm setting and reads open. If I leave the scan list values empty, the Agilent errors but the reading are perfect. Has anyone a clue?

[Ted_H]

Hi there,

Are you using the 34970a driver found on ni.com/idnet?  If so, which one are you using?  Were the VIs working before you converted them to work with RTDs?

Ted

[JLS@Micro]

I am using the 34970 drivers from ni. I start with the intialize, then config temp my problem arises with the "EZ Temperature" sub vi. My RTD's are 1000 ohms the default setting for the Agilent is 100 ohms. I tried writing into the buffer inside the EZ Temperature VI to tell it that I wanted 1000 ohms. The VI's worked great until I switched from thermal couples to rtd's. I have found that if I do not assign a value to the scan list in the EZ temperature vi that I get a reading it causes the Agilent to error but does not effect the functionality of my program. I have stumped everyone around here with this one. It would be awesome to get a solution.

Thanks 

[Dennis_Knutson]

There are different drivers available for download. Could you attach the VI you wrote? Include the modified EZ Temperature.

[Ted_H]

Can you clarify where you are righting 1000 ohms in the EZ Temp VI?  I looked through that VI, but I don't see where that setting can be configured. Also, have you tried using Configure Temperature VI? This VI has an RTD configuration input cluster, try changing the default 100 ohm to 1000 in this cluster.  I have attached a screen shot of this configuration VI.

Ted

Message Edited by Ted H on 12-06-2007 03:57 PM

[JLS@Micro]

Yes I am using the VIs HP34970a found on ni.com. I believe that the problem lies within a command string to the Agilent. I start with the HP34970a "Initialize" followed with the HP34970a "Config Temperature" (which I have configured for RTD, .0091, 1000ohms). All if fine until the next step which is the HP34970a "EZ Temperature" (configured for RTD,.0091). When the EZ temperature vi is run by the software it resets the Agilent to its default setting of 100ohms which results in me getting an "open" reading. I have tried writng a command string inside the EZ Temperature vi to tell the Agilent I wanted to keep the 1000ohm setting and the Agilent got mad, it did not like that. I currently have the program working by excluding the "scan list" from the EZ Temperature VI. It gives the readings I want but causes the Agilent to "beep" an error.

[Dennis_Knutson]

Why would you be calling both Config Temperature and EZ Temperature Scan?You should use one or the other. Look at the example called HP34970A for how to use the Configure functions. That example uses Configure Voltage and Configure Resistance. Your porgram would use just the Configure Temperature. The rest of the code can be used as is, I believe.

[Will_Crowe]

Hi,

Am trying to use the EZ Temperture VI to take readings from thermocouples on an Agilent 34972A (in the 34970 family) and we keep getting errors in the VISA Write VI (code -1073807339). We have set up the device as a VISA device in MAX, have been able to ping it and have even managed to get it to beep in response to some of the other sample VIs in this family (albeit with errors) but we cannot get a reading. Pretty sure we have the syntax in the 'write buffer' input correct (eg. MEAS:TEMP? TC,T, (@101)) but just can't get a reading. Have you any suggestions? They would be greatly appreciated.

Regards,

Will

[Thør]

I'm not sure of the specifics of your setup, but error code -1073807339 is a VISA Timeout error.  Check this KB and see if it helps out.

http://digital.ni.com/public.nsf/allkb/874B379E24C0A0D686256FCF007A6EA0?OpenDocument

[Will_Crowe]

Thanks for that suggestion.

We have now got the Agilent 34972A device to read temperatures through labview but try as we might, we can't get it to do so any quicker than about 20Hz, which is a long way off the 60Hz claimed by the manufacturer for this device.

We have:

1. Contacted Agilent technical support who simply passed on the following suggestions, which we've also tried...

2. Carried out a series of steps through their Agilent interface software and instrument front panel, such as turning off the display, turning off auto-zero etc. This had no effect, although we weren't able to implement all changes suggested.

3. Tried to implement the same suggestions through labview VISA VIs, with code of the form ("DISP OFF") but again with no effect on acquisition rate. Once more, however, we weren't able to get all of the suggested code to work without errors, namely the string, "SENS:ZERO:AUTO OFF,(@101:320)"

Has anyone managed to get this device to read through labview at a rate anywhere close to 60Hz?

Will