Problems with the DC Power supply QL 355TP: I can't set the voltage level

[luisi]

Hi,

I'm trying to control a DC power supply through GPIB. The power supply used is the QL355TP from the Thurlby Thandar Instruments (TTi) company. There aren't drivers from NI to control this instruments, then I have need to download and install the driver from the TTi website: the package that I have installed is the following:  

"QL-P series Power Supplies, (including QL Series II) National Instruments driver (Labview and CVI)"

and I also have installed the following:

"QL-P series Power Supplies (including QL Series II), IVI driver "

So, my problem is that when I'm trying to use the example application of the driver "Ouput DC Volts.vi"; that sets a specific level voltage, doesn't work properly. The application doesn't give any error but it doesn't set the specific level voltage. However, other functions are working correctly like the measurement or the output enable. I have tried many things but I don't know why it doesn't work. 

I have attached the block diagram of the application and the front panel:

I have to say that I just beginning to control instruments using Labview and is possible that this problem would be because I haven't taken account mandatory and elemental things.

Any help is appreciated.

Thank you.

[nyc_(is_out_of_here)]

A diagram is pretty useless for troubleshooting this problem.

You'll need to investigate what is contained in the VI that actually sets the voltage.

[luisi]

I have no idea how I can investigate it. Well, I have opened the VI that sets the voltage level and it seems that is very simple. I have attached the diagram in the following image:

I think that the VI writes the values in the library file of the instrument, but I don't know how I can see where is the error or where investigate to try to fix it. 

I really appreciate if anyone tells me where I can begin to investigate or what I can try to change.

Thank you!

[nyc_(is_out_of_here)]

Either the DLL has a bug, or you are passing in the wrong channel name, or you are passing in the wrong voltage.

It is your job to investigate it, and you are the only one who can do it.

[Dennis_Knutson]

Please turn on I/O Trace in MAX to capture the commands to the instrument and compare them to what is in the manual. If you find a problem, you'll have to contact TT to fix their code unless you have LabWindows/CVI and TT provided the source to their IVI driver. Your other option is to write your own driver using LabVIEW instead. A power supply is usually not a difficult instrument to program.

[Dennis_Knutson · Accepted solution]

p.s. Try changing the decimal separator from comma to period. It's possible the driver does not handle the comma correctly.

[luisi]

Finally, I decided to write my own driver and now I haven't got any problem. 

Dennis_Knutson you are totally right with the decimal separator. The instrument doesn't handle the comma correctly and I have had to program it with the period decimal separator. 

Thanks for your responses.

[satheeshvelu]

Hi Luisi,

I'm using this power supply QL355TP. I have been using Python to control instruments. This PSU I'm not able to get it with Python so going with Labview. Kindly need your support to automate it.