there are a whole range of 14 pin hand controllers , pedals and buttons that fit recent Miller welders... which one you buy or use is a simple matter of your needs and/or preferences....

as you indicated that you wanted a button to trigger either 2T or 4T operation..... here is a thread that goes into button possibilities... it is about a Dynasty 350...... but controllers and buttons are functionally identical between that and your Dynasty 200DX...

http://www.millerwelds.com/resources...-remote-button

this button thread also amply illustrates some of the problems and pitfalls of long distance technical troubleshooting etc.....hard to do remotely without being able to visually see what is going on...



(the controls & pedals for my Dynasty 350 interchange with my Dynasty 200DX and would plug into and operate flawlessly on my friends Synchrowave 250...as will a whole range of aftermarket and third party ones.....)