<R12> A maximum of one (1) VEX Y-cable can be used per Motor Port of the Microcontroller or Power Expander. (You cannot “Y off a Y” to have more than two (2) motors controlled by the same Motor Port.)
a. Teams using the VEX ARM® Cortex®-based Microcontroller can only power one (1) 2-wire Motor per each of the two 2-wire motor ports on the Microcontroller. It is illegal to “Y” off a 2- wire Motor Port.
That’s a shame from a controls standpoint with the faster update rates.