The RF multiplexer is configured as shown in the figure. It is now effectively a 15x1 RF mux.

To select a required channel:

Run the script as shown below 

/opt/rtcds/caltech/c1/scripts/general/rfMux.py

>python rfMux.py ch11

For channel 10 to 16, you can just enter the required channel number and it is routed to the output.

For channel 1 to 8, you only need to input the required channel number as above. No need to run the code again to select ch9 after selecting ch1-8

How the NI-8100 controller works:

Whenever any channel of one switch is selected, the output of the other switch is set to its ch0 (ch1 and ch9 in the figure).

So selecting ch1-8 will automatically select ch9 as output for the other switch. IF you send a command to select ch9 afterwards, the first switch will be automatically set to ch1 and not stay on what you had selected before.