labview DAQ program does not allows me to read 2 different input

[hikaru]

hi
there are 2 problems which i currently face and i hope some experts out there could provide mi with some assistance. firstly, i cannot add 2 DAQ assistant in the same program. And the output obtained from the DAQ assistant are of DC coupling instead of AC coupling.
could someone provide me with some help?
thank you

[Meister]

Hi,

You fail to mention what, if any, error you get and what version of NI-DAQ you are using?, so I will assume you're running into the classical problem using version prior to 7.3.

See the following link for KB describing this known issue:
Multiple DAQ Assistants

Regarding your second issue - could you be a little more specific to what is meant by AC coupling? What kind of AO are you seting up using the DAQ Assistant?

Regards

Anders M
National Instruments DK

[hikaru]

the error that occured is -> Error -200428 occurred at DAQmx Read (Analog Wfm 1Chan NSamp).v
Possible reason(s):

Value passed to the Task/Channels In control is invalid.

The value must refer to a valid task or valid virtual channels.

Task Name: MyVoltageTask

can you help me ??
thank you

[hikaru]

sorry just to add on, the version that i am using is labview 7.1
and the program that i wrote which has error in it is attached below
thank you

[Meister]

Hi

Okay, this is a slightly different issue. It would help me a lot to know, why you are trying to read the same task twice in parallel?
What version of NI-DAQ are you using?

Regards

Anders M
NIDK

[LYu]

Hi Hikaru,

You should only run one task for each measurement type (e.g. AI, AO). You can acquire from multiple channels in one task by specifying all the physical channels you want to read from (e.g. Dev1/ai0,Dev1/ai1 or Dev1/ai0:1).

Thanks,
Lesley Y.

[hikaru]

thank you,
i think i got it by using 1 voltage task but with multiple ports