Solution:

The gain array should be an array with 16 element, and the element should match to the channel number from 0 to 15, no matter what channel we want to scan. For example, we can set gain_array[16]= { ch0, ch1, ch2, ch3, ch4, ch5, ch5, ch6, ch7, ch8, ch9, ch10, ch11, ch12, ch13, ch14, ch15}; And ch0 is the gain code of channel 0, and so on. Attached is the example we made for this case, sorry that QB example is unavailable, this is a C example for your reference. But we believe the driver can also work well with QB if we follow the declaring rule.