Hello,
Please take a look at the following link and see the last example under LabWINDOWs/CVI section. The code you use will be similar in Visual C++ since it is also a C file only.
Link In the WFM_Op, for multiple channels, you have to provide an array.
Please do let me know if the link helps.
Sincerely,
Sastry V
Applications Engineer
National Instruments