Wa'alaikumsalam
Vending machine is trading machine, and all Ulama agree that trading transaction inside the masjid is haram. However, there is difference opinion about "inside the masjid". There are Ulama who classify that all area of masjid are considered as "inside the masjid". There are Ulama who clasify that "inside the masjid" are only the area that for salah such as masjid hall and terrace, while supporter area such as park, parking lane or other rooms that not for salah are considered as "outside the masjid". That's why in some masjid we can find stall or small shop.
Is setting up vending machine in masjid disrespect the masjid?. Better you ask Imam and caretaker in masjid where you want to place this vending machine, are you allowed to put it or not. If they allow you to put this vending machine, let them determine the place to put it.
