The PS/1 coupler is compatible with TMCC, the PS/2 coupler is NOT compatible with TMCC, it'll cook the coupler triacs. It's easy to recognize the PS/2 couplers as they have a flat frame and a patent # on them, the PS/1 couplers don't have that flat frame.
![MTH Coupler Differences MTH Coupler Differences](https://ogrforum.ogaugerr.com/fileSendAction/fcType/0/fcOid/145297442908036347/filePointer/145297442925109284/fodoid/145297442925109280/imageType/MEDIUM/inlineImage/true/MTH%2520Coupler%2520Differences.png)