Communicating with a Fluke Hydra

[epritcha]

We are currently using LabView to communicate with a fluke hydra and scan the channels on a predetermined interval - say 5 seconds. We initially used the LAST? command to acquire data; however, we have found that the buffer seems to trip up occasionally and we get a much longer string of comma separated data back from the hydra - the right data is there, but there is extra data - making the program have channel 4 data on channel 6 say. We suspect it is the buffer trying to purge, or bad timing on labviews part so we tried to use NEXT? to acquire the next values and *CLR to clear the buffer but this did not clear the problem.

How are others acquiring data from a hydra - what series of commands seem to work to eliminate this "timing" issue?

Thanks in advance,

Ewan and Jeff - Advanced Energy

[epritcha]

A clarification - we are not using the *RST command after each cycle, we are actually using LOG_CLR.

Thanks,

Ewan
Advanced Energy

[ooth]

I found that to use the Next Scan command I had to send that command when the Hydra was polling the channels. The problem I ran into was timing my VI to send the Next Scan command at precisely the same time the Hydra was polling. I gave up and instead used the *TRG command. Instead of having the Hydra normally count down until it would scan the channels, I would not have the Hydra in scan mode at all. When I wanted a reading I wound send a *TRG command followed by the Next Scan command. This solved my timing issue when using the Next Scan command. Hope this helps you.

-John Liscio

[bryan@bissell]

I am also haveing problems and I am new to this, any chance you have some code you could share that works with the hydra. I have a 2625A I am trying to communicate with, and I keep getting an error 17 for the example included with the driver files.

Any help would be great.

Thanks
Bryan

[ooth]

I went back and looked at my Hydra VIs, and found I created my own generic hydra command VI. I then replaced all the serial VIs with my VI, which uses VISA by the way. Here is my Hdyra.llb and a simple example that gets a scan's data using the NEXT? command. I also included part of the OPEN G String.llb that I use to solve the comma problem that was brought up in the first post. Hope this helps. I'm using LabVIEW 6.1.

[st168]

I'm writing a labview programe to drive the Fluke 2625A to read 20 channels temp. I have tried your attached programe. I cannot read the temp. Could you suggest me any ideas?  thank you.

[ooth]

I added some comments to the "Fluke VISA command.vi", this is the VI that I created and inserted into all the other VIs in the llb.

Hope it helps.

Also this VI was written expecting the Hydra to be connected through the serial port so it might need changed if using the GPIB.