Switch-wise I don't see any problems. I would use the first switch to select NCE or QSI programing, then feed the output of that switch to the 2nd switch which would be for programming or ops.
But keep in mind that if you accidentally place a loco across the gap between your programming section and hard-wired mainline DCC (one truck or wheelset on the main line and the other truck or wheelset on the programming section) then you could theoretically blow up your programmers.
Having warned you, friend of mine also uses a section of his mainline with a DPDT switch for programming and he has not had any problems. His section is fairly long and no mainline locos are anywhere nearby it when he is programming.
---In QSIndustries@..., <james@...> wrote :
I have a programming track on the main. With the use of a DPDT toggle I have safety sections on
both sides of the programming track. The input comes from the NCE command station. I am thinking
about adding an additional DPDT toggle, so I can use either the programming output from the NCE
command station or the programming output from a QSI programmer attached to my computer.
I don't think this is any problem unless someone knows a reason otherwise.