Get a list of physical channels

[Oksana]

Dear community,

I am using DAQmx8.3  C API under VS.net.

I need to acquire a list of physical channels of a device to make a user able to select a channel.

After extensive navigation through discussion forums, I found a reference to DAQmxGetDeviceAttribute function.

This function is not listed in the C API help, but its prototype can be found in NIDAQmx.h, which means the library supports it.

int32 __CFUNC_C DAQmxGetDeviceAttribute (const char deviceName[], int32 attribute, void *value, ...);

Can anyone provide a description how to use it?

I am not familiar with LabView where, as I understand, attribute is a key concept. 

As for the device, I will be using cDAQ9170, (until it arrives USB-6009), but I think this function does not care.

thanks,

Oksana

[Abhinav T]

Oksana,

You can get a list of physical channels using the following functions:

DAQmxGetSysDevNames(char *data, uInt32 bufferSize); - this gives you all the devices that are configured under DAQmx on your system
data is the string that contains all the device names

DAQmxGetDevAIPhysicalChans(const char device[], char *data, uInt32 bufferSize); - this gives you all the physical channels on a device
device[] input is a device name from the first function
data is the string that contains all the physical channels

I wrote the following code as an example:

    char        devices[11];
    char        devName[4];
    char        channels[1000];
    DAQmxErrChk (DAQmxGetSysDevNames(devices, 11));
    printf("%s\n",devices);
    for (i;i<4;i++)
        devName[i] = devices[i];
    DAQmxErrChk (DAQmxGetDevAIPhysicalChans(devName, channels, 1000));
    printf("%s\n",channels);  

Hope this helps!

Abhinav T.
Applications Engineer
National Instruments

[Oksana]

Hello Abhinav,

It did help! And it works.

I would define  devName[5]; to include \0 character, and accommodate the for loop appropriately in the example.

In my case, it doesn't really matter, I have only one device anyway.

Thanks a lot!

Oksana