Hi,
When using the SCXI-1127 you have to make two separate calls to connect chx to abx. You have to explicitly connect chx -> comx and then comx -> abx. Remember that you can make one call to connect comx -> abx at the beginning of the program and then every time you make a call to connect chx -> comx then chx will be connected to abx. In a way, after the first connection is made to abx, then it only takes one call to connect chx to abx.
Additionally, if you want to make predefined channel routes through multiple switches then you can use the Switch Executive software.
http://www.ni.com/switchexecutive/
Hope this helps!
Erick D.
NI Applications Engineer