change virtual channel settings USB6221

[praondevou]

Hello,

first of all, thanks for anybody reading this and maybe come up with an idea.

I'm confronted with an USB-6221 device on which several analog input channels are being used to measure current (voltage output of Hall sensors)

They are set to +10V / -10V. My question is, how do I change these settings, e.g. to +-5V? The person who installed it is no longer working here, and nobody knows how to configure the device.

On the PC that was being used there is the MAX installed, it also shows me the device, but I don't see an option to change settings in the USB-6221.

I read that I can create virtual channels etc with the assistant, but that's not what I want to do, I want to modify settings...

Everything else works, e.g. switching digital outputs on/off, take readings from the analog inputs etc.

I also would like to change the sample rate that is currently being used.

Is there any other software I need? Or can someone guide me in the right direction? I read the Getting Started manuals etc, but it's still not clear to me.

Thanks in advance

PS: If necessary I can provide more data on monday when I'm back in the company.

[niNickC]

Hello,

This firstly depends on what software you are using to interface with the USB 6221. Currently, how are you acquiring the data from the device? Are you using LabVIEW?

MAX is used for device setup, configuration and testing, you cannot adjust the settings for individual acquisitions here (such as data rate and input range)

If you are using labVIEW the DAQmx getting started guide on ni.com is a great resource for helping to explain how to use NI DAQ devices (such as your 6221) with labVIEW.

This can be found here:

http://zone.ni.com/devzone/cda/tut/p/id/5434

Let me know how you get on with this and if you have any more questions, feel free to post your code and I can give you a few tips on how to proceed.

Nick

[praondevou]

Thank you for your response.

I think that is the problem then. For data acquisition they are currently using a software that was written by the person who installed the device. I don't have access to the source code.

So if I understand you right, the analog input range sample rate etc is not being adjusted inside the device but is determined by the software that is used to retrieve the data, is that correct?

[Dennis_Knutson]

The analog input range, sample rate, etc. that is inside the device can be set by the software so your question does not make much sense.

[niNickC]

Yes that is correct, this will often be done with LabVIEW as this allows for the greatest control and without the need for coding in a procedural language (like C).

You can use Signal Express to get data from your device and this is available in a free light version. This allows you to acquire data from your device and adjust setting such as sample rate and voltage range without the need for a self-written program. It can be used to quickly acquire and present data but does not include any of the advanced programming features which are included in say LabVIEW.

This can be found here:

Signal Express

[praondevou]

It did make sense to me :-). Maybe I didn't make myself clear...

There could be two options IMO that would make sense with a device like this, and it wasn't clear to me which one is used:

1. The DAQ device is configured once with all the configuration data needed, like sample rate, analog input range etc. Then when I want to retrieve data I trigger the acquisition process from my PC and start transferring the data from DAQ to PC.

OR

2. Everytime I start the software on my PC the configuration is passed to the DAQ and then I start retrieving data. This is what is obviously used in my case. I found out that there is a parameter in this custom written software that let's me change the sample rate... However the programmer didn't leave an option to change the analog input range.

Thanks for your help

[Dennis_Knutson]

The configuration is stored externally in MAX or in a main program. The main program can be written to load one or the other and then the main program starts the daq device with those parameters. If you do not have one or more tasks in MAX, then the programer did not provide a means of loading external parameters. This is actually kind of typical since you don't want people randomly changing things and damaging the hardware.

[Dennis_Knutson]

p.s. Why don't you have access to the source code?