Barrel size and limitation of MTH remote commander 50-1033

1. 5.5mm (OD) / 2.1mm (ID)

2. Two types of PS2.0.  One called PS2-5V (uses a 9V-size battery), other called PS2-3V (uses a dual AA/AAA battery).  The terminology -5V and -3V is confusing since the voltage reference is to an internal digital voltage which an end-user really doesn't care about, can't "see", and can't even practically measure.  The newer PS2-3V can additionally operate on DC track voltage.  PS2-3V boards coincided with MTH's foray into large-scale "One-Gauge" engines which generally use DC; yes, there are a minority of large-scale layouts that use AC.  Likewise there are a minority of O-gauge layouts that use DC.

Anecdotal evidence strongly indicates that the more recent PS2-3V electronics is more reliable than PS2-5V.  Due to the way the earlier PS2-5V boards are assembled, they can be difficult/impossible to repair.

That is a mis-print in the DCS Remote Commander manual.  It can control all PS2 engines (-5V and -3V).  As you highlighted, the key is to make sure the engine ID is correct.

Thanks for the clear and detailed response STAN2014, I feel better now having special ordered a remote commander and 1/2 my engines are older PS2 with the 9v batteries. 

I've run 5V PS/2 engines with the DCS Remote Commander with no issues at all.  As long as they've been factory reset, all is well.

Thank you Sir and Happy New Year!